Out of the Abundance of the Heart

Can We See Into Someone's Heart?

Have you ever wished you could just see into someone's heart — have this spiritual x-ray vision so you could know, what is in this person's heart? Are they actually a Christian or not?

Maybe you've been burned before. You followed this pastor, you liked him, you watched his sermons online, and then he fell away from the faith, and you thought, man, I thought he was a Christian. Or maybe you had a friend growing up — you went to youth group together, went to church together, you were both Christians, you evangelized together — and then that person goes off and walks away from the faith. You think, man, I wish I could just see into people's hearts, because it really matters for our life what is actually in that person's heart.

There are a lot of people who claim to be Christians. A lot of people in the world who claim to be Christians. But we want to know — are they actually, though? In their heart, are they actually a Christian? Think about it: if you're thinking about dating this guy — first of all, he claims to be a Christian, hopefully you're there, and if he doesn't claim to be a Christian, you're already off on the wrong start — but you're dating this guy, he claims to be a Christian, and you think he is, you're pretty sure he is. He goes to church with you, he sings the songs, he reads his Bible sometimes. But how do you know for sure, in his heart, that he actually is? Is there a way to tell?

You can also think about this with our children. You're raising your children. You want them to come to believe in Christ, you want them to be saved. And you're looking at their life and you go, maybe — they come to church, they say they're a Christian, it seems like they aren't doing anything too crazy. But how do you know the state of your child's heart? How do you know how they're actually doing in there? Do they really believe, or are they just doing what I tell them to do because I'm a Christian?

You're looking for someone to mentor you, to disciple you — someone more mature in the faith to help you along. How do you know this person is actually more mature, actually a wise Christian who can help you? Is there a way to see into their heart? It'd be so nice to just pull back the spiritual curtain, get God's-eye view, and go, yeah, there's a heart that is actually captive to Christ.

And forget about all these other examples for a moment — what about your own heart? Do you ever look at your own heart and go, what am I doing? Am I a Christian? Do you ever sin again — burst out in anger against your family again, click on that thing online again — and go, man, am I a Christian? Because when I'm looking at my heart, I'm having a hard time seeing what's going on in here. I think I'm a Christian, I go to church, I believe in Christ, but I've got a lot of sin going on in my life. How do I know for sure that my heart has been totally taken by Christ?

Well — spoiler alert — we're not going to actually get x-ray vision to see people's hearts perfectly. But this is actually where Jesus takes us. At the end of his Sermon on the Plain in Luke chapter six, Jesus takes us to the heart. As he's ending his sermon, he goes, "Let's look at your hearts and what's actually going on there. "

So if you have your Bibles, please open them up to Luke chapter six. We're picking up where we left off last week, at the very end of Luke chapter 6. We've been going through this sermon from Jesus, and last week Jesus was teaching us that we should correct others only once we've corrected ourselves. The illustration he ended on — the image he uses to teach us that — is the idea of having a speck or a log in your eye. He's like, yeah, you see somebody with a speck in their eye, that's bad, you want to take it out. But make sure you clear your own eye out first.

And I think the question that follows naturally, as we're in this mode of self-examination — what's in my eyes? Can I see? Can I see clearly enough to lead this person? Is this person seeing clearly enough to lead me? Are we both just going to fall into a pit? — it brings us back to this question of, well, how do you know, man? If there's something in my eye, how can I see it? If I'm looking at somebody else, how can I tell how they're doing? How do I know if they're blind or if I'm blind? In other words, what's the state of our heart? If we're supposed to be correcting others, guiding others, but we don't want to be blind, we don't want to be doing it with stuff in our eyes — how do we know the state of our heart so we can do that well?

That's where Jesus goes, following that illustration about specks and logs. He's going to tell us: how do you examine a heart to know what's in it? To know if someone is blind or not. So look at Luke chapter 6, starting in verse 43.

This is what Jesus tells us. If you want to know what's in someone's heart, you have to look at their works.

Trees, Fruit, and the Nature of the Heart

That's what he says in this first paragraph, and he does it by way of an analogy from nature. He starts talking about good trees and bad trees and what kind of fruit they produce. Here's what he's getting at.

Trees can only produce based on the nature of the tree. An apple tree produces apples. A grapevine produces grapes. A thorn bush produces thorns. Because it's an apple tree. Because it's a grapevine. That's what it does. So when he's talking about good trees and bad trees, he's not talking about a rotten apple tree producing rotten apples. He's talking about whether it's a good tree — an apple tree that produces apples — or a bad tree, a thorn bush, that is useless and just produces thorns. He's talking about kinds of trees entirely, the very nature of the tree itself. In verse 44 he talks about figs from thorn bushes, grapes from brambles. The good tree is a grapevine that produces grapes. The bad tree is a bramble that produces no fruit, just thorns. Each tree is known by its own fruit.

What he's getting at is this: you might be unsure what kind of tree you're looking at. Let's say you buy a new house and the previous owners tell you, "Hey, there's a pear tree in the back. " "Oh, a pear tree, cool. " And you're waiting for it to produce pears. The first fall comes around, no pears. You're telling everybody, "Guys, look at this cool pear tree in my backyard. " And then finally, one year, you see it's budding, it's starting to produce fruit. Okay, here it comes. And there's an apple on the tree. You go, wait — my pear tree's producing apples? No, you had an apple tree the whole time. You just had no idea. You know the tree by its fruit.

It's obvious in nature — we all know this. Things produce based on what they are. You can go beyond trees too. What does a dog do? A dog barks. Why? Because it's a dog. What does a cat do? It meows, because it's a cat. You see this mangy-looking thing out on the street and think, I have no idea what that is. Then you hear it meow. Oh, it's a cat. Because cats meow. It's about the nature of the thing itself.

We all know this is true in nature — you know the thing by its fruit. Well, Jesus takes this truth from nature and says, guess what, guys? That's true of human beings as well.

Verse 45: "The good person, out of the good treasure of his heart, produces good. " Just like an apple tree produces apples, a good person — if by their very nature their heart is good — is going to produce good things, because that's what they do. And the evil person produces evil things out of the evil stuff in his heart, because that's his nature. He can't start producing good things because he's evil. "Out of the abundance of the heart, his mouth speaks. " You can tell what's in a person's heart by the things they do — and, Jesus points out at the end of verse 45, by the things they say. Sometimes people might act really well, keep themselves buttoned up, but then something slips out of their mouth. "Oh no, that's not really me, man. I didn't mean that. " It came from somewhere. It came from your heart. Just like in nature, people can only produce based on what they are inside.

So if you want to know what's in someone's heart — your child's heart, your boyfriend's heart, your own heart — you look at the works, the deeds, the words. Those things reveal what's actually going on in the heart, because all of us act according to our nature, what's in us.

Now, that sounds easy. Three verses, easy. Just look at the fruit, then you know what's in the heart, done. Except we know in real life it's not always that easy to tell.

We all know people who are not even Christians — abjectly not Christians — but they're good guys, good neighbors, good friends. If you're thinking, all right, if they're doing good things, that means there's good in their heart — here's a good neighbor, he's good to his pets, whatever — does that mean he has a good heart, even though he's not a Christian? And of course, all of us know people who claim to be Christians but are pretty mean, not that generous, not that loving. And you're going, I'm seeing a lot of evil things in this person's life, but they're claiming to be a Christian. Does that mean their heart is still evil?

Think of the person who claims to be a Christian, comes to church every Sunday, sings the songs, reads their Bible. And then you're talking to them and you notice they often lie a little bit. You catch them in it — "Oh yeah, sorry, I didn't mean that. " And they just keep lying. You go, "Hey man, you know lying's a sin, right? " And he goes, "Hey — I'm saved by grace, okay? Have you read the Bible? Let me show you this verse. " And every time you try to press them on sin, they start quoting the Bible about grace to you, and something's off. You think, what is going on with this person? What's in their heart? Are they actually saved? Because I'm seeing things that look like good fruit — they're coming to church, reading the Bible, quoting Bible verses — but something seems off.

Or think about the person who, as far as you can tell, is genuinely a Christian. Their life seems spotless — they're generous, warm, loving to people, they help the poor, they know their Bible backward and forward. And then you're in a conversation with them and they say, "Hey, have you seen this verse? Did you know this verse actually teaches that Jesus is not God? " You're like, whoa, man — I thought this guy was a Christian. Everything about his life was telling me he was a Christian, and now he's saying the Bible teaches heresy?

And again, to stop looking at other people for a second and look at our own hearts: do I really have good fruit or bad fruit? I sin a lot still. Does that mean I'm evil? I'm looking at my life, and I sinned like a hundred times this week. Does that mean my heart is still evil, or what's going on? Where are the good fruits? I feel like I'm a Christian, I want to be a Christian, I'm following Christ, and I feel like I'm not seeing fruit in my life.

So as easy as it sounds — just look at the fruit and you'll know what kind of tree it is — in real life it can get a little harder to discern. So let's think for a moment about what good works actually are. What does Jesus mean? What is a good fruit versus an evil fruit, and how do we discern that in someone's life?

Good Fruit Always Starts With Repentance

Here's what I think is the main principle for discerning between good and bad fruit: true good works that come from a truly good heart always start with repentance. That's the key. If it's a real good work coming from a heart that has actually been changed to be good, repentance has to be involved somewhere — or else it's actually not a good work.

The Bible, everywhere in the New Testament, ties good works together with repentance. Just a few quick examples. Luke 3: 8: "Bear fruits in keeping with repentance. " That exact phrase is repeated word for word in Matthew as well. And later in the book of Acts, when Paul is before Agrippa and Agrippa asks, "What's going on with you, Paul? " Paul says, "I'm going around preaching repentance and telling people to do good deeds in keeping with repentance. " Explicitly, in multiple places, the New Testament tells us good deeds should be in keeping with repentance — your good deeds should show that you've repented, the repentance should shape what you're doing.

How about Romans 6: 20–22? "For when you were slaves of sin, you were free in regard to righteousness. But what fruit were you getting at that time from the things of which you are now ashamed? For the end of those things is death. But now that you have been set free from sin and have become slaves of God, the fruit you get leads to sanctification and its end, eternal life. " There's a before time — you're evil, doing whatever you want, not caring about God, and you've got evil fruits leading to death. Then something changes: repentance. You become a Christian. God redeems you. Now there are different fruits. The way good fruits start is with repentance.

And Galatians 5 — the fruit of the Spirit, probably the first place your mind goes when you think about good fruit. But notice what Paul does right before he lists those fruits. In verse 19, he lists all the works of the flesh: sexual immorality, impurity, sensuality, and then about twenty more. Why does Paul talk about all the evil things first, before the good things that come from the Spirit? Because there's a change in the middle — just like Romans. There's evil, then repentance, then the Spirit indwells you, then good fruits happen.

So when we're looking at people and asking, what's in their heart? — repentance has to be there somewhere for there to be any good fruit at all. Good fruits start at repentance.

And this makes sense, because repentance is the only way to get a new heart. Jesus makes it totally clear in this passage that the good works of a good person come out of their good heart. But the Bible also makes it extremely clear that humanity's hearts are wicked. Outside of Christ, this could not be clearer. Jeremiah 17: "The heart is deceitful above all things. " Ephesians 2: you were dead in your sins — your heart wasn't even beating. Romans 3: no one is righteous, not a single person. Mark 7: Jesus says, from within, out of the heart of man, comes evil. All over the Bible, the message is the same: outside of Christ as a natural human being, your heart is evil.

So you read this passage and you go, okay, so an evil heart produces evil. How are we ever going to have a good heart to produce good?

That's why, all throughout the Bible from beginning to end, God promises to give us a new heart. The most famous: Ezekiel 36, "I will give you a new heart, and a new spirit I will put within you. And I will remove the heart of stone from your flesh and give you a heart of flesh. And I will put my Spirit within you and cause you to walk in my statutes and be careful to obey my rules. " And then of course in the New Testament: 2 Corinthians 5: 17, "Therefore, if anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come. " Or Ephesians 5: 8: "For at one time you were darkness" — by nature, your very nature was darkness — "but now you are light in the Lord. "

This is the gospel. Though we were evil, though we hated God, though we didn't care about any of it, Christ died for us. He took the penalty for our sins, he rose again to new life — and he didn't just take away the penalty. He does heart surgery. He takes out the heart of stone and gives us a heart of flesh. He takes us from being thorn bushes, bramble bushes that produce nothing but thorns, and changes that thorn bush into an apple tree that bears fruit. Our very nature is changed when Christ saves us, and the way we access that is through repentance.

So what are the good works that prove a person has a changed heart? You're looking specifically for works that scripture says come from God, that we can't produce on our own.

We often think of the fruit of the Spirit from Galatians 5 — love, joy, peace — and we figure we're just looking for a nice, kind, gentle person. But the whole New Testament talks about a much wider range of good fruits that can only come from the Spirit, and the key behind all of them is that your heart has to be changed for them to even be possible.

Back to Romans 6: 22 — the fruit leads to sanctification. So one of the main fruits you're looking for is holiness, progress in sanctification. Not perfection, but a movement toward holiness. Somebody who actually cares about what God says and whether their life is lining up with God. John Calvin in his Institutes, in his section on repentance, puts it this way: "The more a man studies to conform his life to the standard of the divine law, the surer signs he gives of his repentance. " When you meet somebody and you're asking, should I date this person, is this mentor actually mature in the faith? — you're not asking, are they perfect? You're asking, is there any evidence that they're fighting sin? That they're studying God's law to try to be more like him? That's a fruit that cannot come from a thorn bush.

How about Ephesians 5: 9? "The fruit of light is found in all that is good and right and true. " You were darkness, now you're light. Does this person agree with what the Bible says is right and wrong? Or are they celebrating things that are evil? They might look like the kindest, nicest person ever and come to church with you, but then they celebrate things that are evil. If their heart has actually been changed to the light, they will only celebrate what is good and right from what God says.

How about truth? Think of that person who seems to have their life together — generous, the model Christian — and then you hear them talking about the Bible, and they're twisting it. When the Bible says something is true, they go, "Well, actually, here's something else. " That is showing an unrepentant heart that's not letting scripture change it, resisting the truth of God's Word. But when you show someone the truth and they go, "Oh, I haven't seen that verse before — I need to think about that more" — that's the sign of a soft heart that cares about truth, a heart that's actually been changed.

One more fruit we don't often think about: Revelation 16: 9. The angels are pouring out the bowls of God's wrath on the unrepentant, and they "cursed the name of God who had power over the plagues — they did not repent and give him glory. " Not repenting means not giving God glory. So giving God glory is a sign of a changed heart. Do they have any sense in their life that they're trying to live for God's glory, or are they still only thinking about themselves? Do they thank God and praise him for what he's doing? Because those who strive for God's glory and praise him for it are those whose hearts have been changed.

And going back to those fruits of the Spirit — I think we underestimate them a little. "Love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control. " I'll hear people say, "Well, he's a super nice guy, man. He's kind, he's gentle. " But we need to look a little harder. Is it just being a nice guy, or is it a little deeper than that?

Think about peace. Do they have the kind of peace that Philippians 4 talks about — the peace that surpasses all understanding that can only be found in Christ? When they think about their job, or the state of the world, is it just anxiety — or is it, "Man, I need to repent of that anxious thought I just had, because I'm not resting in Christ's peace like I should"? That's a peace that isn't possible outside of Christ — truly, in any circumstance, trusting that you are with Christ.

Or self-control. We might think of this as getting up and going to the gym every morning. But this is talking about self-control over your whole life, including over sin. Does the person ever actually stop themselves from sinning? Because if they never show that kind of self-control — if they just run headlong into sin every time — that might be a sign that their heart isn't there.

Examining Your Own Fruit

Most importantly, I think we need to apply this level of scrutiny to our own hearts. Maybe you're still sitting there going, okay, I'm thinking about all these fruits and I still don't know, man. I still sin a lot. How do I tell in my own life what's a good fruit and what's an evil fruit?

I think that's exactly what Jesus wants us to do here. In Matthew, when Jesus preaches this same section, he explicitly makes it about false teachers — "Hey, false teachers are going to come. Look out for their fruits. " Here in Luke, Jesus just says, look for fruits. And I think the emphasis — though it certainly applies to others — is that we should be looking at our own fruits. Look at our own hearts. What is overflowing from our hearts? Has your heart repented or not?

The tree analogy is really helpful here, because again — this is talking about kinds of trees, not about a healthy apple tree versus a sick one. It's not asking whether you're a fruitful apple tree or a struggling one. It's asking: are you an apple tree or are you a thorn bush? So if you see any sign in your life that there are apples — that something in your nature has actually changed — then you're on the right track. It doesn't mean you're going to be perfect.

Apple trees can have rotten apples. Worms can get in. Bugs can eat all the apples off. There can be dead branches that need to be cut off — ugly, taking up a huge piece of the tree, no apples on it. Cut that thing off. But you're still an apple tree. You can have a year where not a lot of apples are coming out and think, I don't see a lot of good works in my life right now. But are there any? And hopefully you're trying to grow in those. The point is, you're looking for: are you an apple tree at all? Not, am I a perfect apple tree with millions of great apples?

So to sum up all of this fruit material, here's how J. C. Ryle puts it: "Let it be a settled principle in our religion that when a man brings forth no fruit to the Spirit, he has not the Holy Ghost within him. Let us resist, as a deadly error, the common idea that all baptized people are born again and that all members of the church, as a matter of course, have the Holy Spirit. One simple question must be our rule: what fruit does a man bring forth? Does he repent? Does he believe with his heart on Jesus? Does he live a holy life? Does he overcome sin? Habits like these are what scripture calls fruit. "

Those are the fruits we're looking for. When you're looking at that potential spouse, looking at your child, looking at your own life — you're looking for repentance, for belief, for overcoming sin. Those are the good fruits that can only come from a tree that's been completely changed.

That doesn't mean it'll always be easy to tell right away. You might be looking at that tree and go, I think it's an apple tree — I haven't seen fruit in a long time — and it might turn out in the end that it's not. We're not going to do this perfectly, because it is not actually x-ray heart vision. We're only working with what we can see: what people do and say. But at the end of the day, it will eventually become clear whether you're seeing actual fruits of repentance or not. That's what we're looking for. We're called to examine our actions to see what's in our hearts.

Two Foundations: What Are You Standing On?

Jesus is going to move on from this section and keep making the same point. He's doubling down, calling us again to look at our hearts. What he's doing here in this last paragraph of the Sermon on the Plain is showing us the stakes of where your heart is at. The stakes are as high as they could possibly be. What is in your heart matters — not just so you can live wisely, not just so you can fight sin in your life. The state of your heart matters for whether you will be able to stand before God on the final day.

Listen to this last paragraph, starting in verse 46.

We need to examine our actions so we can know what's in our hearts, because only those with a repentant heart can stand before God in the judgment.

In verse 46 he says, "Why do you call me Lord, Lord, and not do what I tell you? " This is exactly the same thing as the fruits. The fruits are placed right before this for a reason — so we can understand what this verse is saying. Those who have had their hearts changed by Christ do what he says. Jesus is talking about professing Christians, people who sit in the pews, come to church every week, sing the songs with us. As far as you can tell, they're a Christian — they claim to be one. They say, "Yes, Jesus is my Lord. I follow Jesus. " Jesus is saying, all right, look at their fruits. Look at their fruits to see if they actually follow me.

Do they claim the name of Christ and obey him? Then yeah, they're a Christian. Their hearts have been changed. Do they claim the name of Christ and then not obey what he says? That person is a hypocrite, as Jesus said back in the correcting-others section. Their heart has not been changed. You can say all you want, but at the end of the day, do your actions prove that you follow Christ? You can call yourself a Christian, you can go to church, but if there are no good works, no repentance, no obedience — that person is not a Christian. Their heart is still evil. It hasn't been changed by Christ.

This is not works-based salvation. This is the fruit tree thing. It's nature. The people who've been changed by Christ do what he says. The people who haven't don't.

And to help us understand that, Jesus uses another analogy from real life that everybody understands: two houses. Actually, it's more about two foundations, because on top they just look like two regular houses. Two guys go into a neighborhood, they're going to build. Two houses that look alike from the outside. But what's underneath is what's different.

The first guy digs. He's like, "I need to build a house, and I want it to have a firm foundation. " In Greek, there are actually three verbs here: he digs, he digs even deeper until he hits bedrock, and then he places the foundation on the bedrock. He's doing it right — not just throwing it up. He's going to dig as far as he needs to until he hits that rock. And his neighbor looks over and goes, "What are you doing digging over there? There's perfectly good ground right here. " Boom, house.

Two houses that look the same from the street. One has a foundation on the rock. The floods come, and the one founded on the rock stands — while the other one, sitting on topsoil, gets completely destroyed. "It fell, " verse 49 says, "and the ruin of that house was great. " It didn't just float away a little bit. It was destroyed, splintered, gone, irrecoverable. The ruin was great.

And what is this flood hitting these houses? I think it's the judgment of God. Three reasons. First, in the Bible, water and floods are a symbol for judgment all throughout scripture. In Genesis, God floods the world to judge the evil. In Revelation, there's no sea anymore in the new heavens and new earth — because judgment is over. Second, we're talking about trees, and in most places in the New Testament where Jesus or John talks about trees, we're talking about chopping them down and burning them. If a tree bears fruit, good. If it doesn't, watch out — it's going to get chopped down and burned in unquenchable fire. That's judgment. Trees that bear fruit survive, trees that don't get burned. Third, if you read the parallel passage in Matthew, Matthew makes it explicit: people will say "Lord, Lord, " and Jesus will say, "I never knew you, depart from me" — and then the flood comes and destroys their house.

Is it about living wisely? Yes. Is it about surviving the storms of life? Yes — if your heart has been changed by Christ, you're going to persevere. But ultimately, what's happening here is: what are you standing on when God's flood of judgment comes? Are you standing on loose sand that gets wiped out from under you? Or are you standing on the rock that is Christ, which will not be swept away?

And I think the reason this account in Luke doesn't include the explicit false-prophet language from Matthew is that the point here isn't about watching out for someone else. Jesus is saying, look at your own heart. Do you do what I say? Because if not, you might not survive when that flood of judgment comes. If you don't care about my words at all, if Scripture never convicts you, if you've never changed your life because of what Scripture says — it might be that your heart is still hard and unrepentant, and that heart will be swept away in the judgment.