What did Jesus mean by "you will know them by their fruit?"

by Luke Wayne

"Beware of the false prophets, who come to you in sheep’s clothing, but inwardly are ravenous wolves. You will know them by their fruits. Grapes are not gathered from thorn bushes nor figs from thistles, are they? So every good tree bears good fruit, but the bad tree bears bad fruit. A good tree cannot produce bad fruit, nor can a bad tree produce good fruit. Every tree that does not bear good fruit is cut down and thrown into the fire. So then, you will know them by their fruits," (Matthew 7:15-20).

Jesus' words here are a powerful warning that there are many who come in His name who are actively seeking to lead us away from the truth, and we are to be on guard against this threat. Wolves are not a thing that sheep should only concern themselves with when things get obviously bad. Sheep must always be alert and ready for such predators. And if the wolves can dress up as sheep, the threat becomes infinitely more severe. Jesus chose very strong words here to emphasize our need to be ever vigilant against a subtle but hostile threat to us and our brothers and sisters in Christ.

But how are we to identify a threat like this? If the false prophet looks and acts exactly like a sheep, and is only inwardly a wolf, how do we figure it out? We cannot see the contents of the heart. Jesus, therefore, gave us a sign to look for: "You will know them by their fruits." This, of course, raises a further question. What are the fruits? The Gospel of Luke gives us additional details that help to clarify:

"For there is no good tree which produces bad fruit, nor, on the other hand, a bad tree which produces good fruit. For each tree is known by its own fruit. For men do not gather figs from thorns, nor do they pick grapes from a briar bush. The good man out of the good treasure of his heart brings forth what is good; and the evil man out of the evil treasure brings forth what is evil; for his mouth speaks from that which fills his heart," (Luke 6:43-45).

We, therefore, will know the prophet by what he speaks. What comes out of his mouth will give him away. He may appear clean and upright to us on the outside in every way, but if deceit and falsehood are in his heart, this false teaching, false prophecy, and others perversions of the truth will come out of his mouth. The fruit of a fig tree is figs. The fruit of a grape fine is grapes. The fruit of a prophet is his prophecy. Jesus elsewhere said:

"Either make the tree good and its fruit good, or make the tree bad and its fruit bad; for the tree is known by its fruit. You brood of vipers, how can you, being evil, speak what is good? For the mouth speaks out of that which fills the heart. The good man brings out of his good treasure what is good; and the evil man brings out of his evil treasure what is evil. But I tell you that every careless word that people speak, they shall give an accounting for it in the day of judgment. For by your words you will be justified, and by your words you will be condemned," (Matthew 12:33-37).

James, seemingly drawing on Jesus' words, offered similar words about what the fruit is that exposes the heart:

"But no one can tame the tongue; it is a restless evil and full of deadly poison. With it we bless our Lord and Father, and with it we curse men, who have been made in the likeness of God; from the same mouth come both blessing and cursing. My brethren, these things ought not to be this way. Does a fountain send out from the same opening both fresh and bitter water? Can a fig tree, my brethren, produce olives, or a vine produce figs? Nor can salt water produce fresh," (James 3:8-12).

God used a related analogy when He was addressing the false prophets of Jeremiah's day:

"'I have heard what the prophets have said who prophesy falsely in My name, saying, ‘I had a dream, I had a dream!’ How long? Is there anything in the hearts of the prophets who prophesy falsehood, even these prophets of the deception of their own heart, who intend to make My people forget My name by their dreams which they relate to one another, just as their fathers forgot My name because of Baal? The prophet who has a dream may relate his dream, but let him who has My word speak My word in truth. What does straw have in common with grain?' declares the Lord. 'Is not My word like fire?' declares the Lord, 'and like a hammer which shatters a rock? Therefore behold, I am against the prophets,' declares the Lord, 'who steal My words from each other. Behold, I am against the prophets,' declares the Lord, 'who use their tongues and declare, ‘The Lord declares.’ Behold, I am against those who have prophesied false dreams,' declares the Lord, 'and related them and led My people astray by their falsehoods and reckless boasting; yet I did not send them or command them, nor do they furnish this people the slightest benefit,' declares the Lord," (Jeremiah 23:25-32).

Especially note the phrase, "The prophet who has a dream may relate his dream, but let him who has My word speak My word in truth. What does straw have in common with grain?" The genuine word of the LORD is life-sustaining grain while the false prophets bring forward only a dead, dry stalk. Again, you will know the true and false prophet by the content of their words. Elsewhere, Jesus plainly warned:

"for false Christs and false prophets will arise, and will show signs and wonders, in order to lead astray, if possible, the elect. But take heed; behold, I have told you everything in advance," (Mark 13:22-23).

We must hold the words of every professing Christian leader to the teachings of Christ and the words of Scripture. The human heart longs for the new and novel, but God's word is sufficient, and we have been warned to flee from those who contradict it or go beyond it. It doesn't matter how nice a guy it is. It doesn't matter how holy, prayerful, and pious a life they appear to live. It doesn't matter how much they look like a sheep. The things they teach will give them away, and Jesus told us to examine the fruit of their mouth rather than merely the white, wooly clothes of their lives. Peter further warns us:

"But false prophets also arose among the people, just as there will also be false teachers among you, who will secretly introduce destructive heresies, even denying the Master who bought them, bringing swift destruction upon themselves. Many will follow their sensuality, and because of them the way of the truth will be maligned; and in their greed they will exploit you with false words; their judgment from long ago is not idle, and their destruction is not asleep," (2 Peter 2:1-3).

These false prophets and false teachers come secretly to introduce destructive heresies. It is their teaching that is so dangerous, and it is their teaching that we need to be careful to evaluate. John likewise says:

"Beloved, do not believe every spirit, but test the spirits to see whether they are from God, because many false prophets have gone out into the world. By this you know the Spirit of God: every spirit that confesses that Jesus Christ has come in the flesh is from God; and every spirit that does not confess Jesus is not from God; this is the spirit of the antichrist, of which you have heard that it is coming, and now it is already in the world. You are from God, little children, and have overcome them; because greater is He who is in you than he who is in the world. They are from the world; therefore they speak as from the world, and the world listens to them. We are from God; he who knows God listens to us; he who is not from God does not listen to us. By this we know the spirit of truth and the spirit of error," (1 John 4:1-6).

What they say about Jesus, what they teach us to believe, what comes out of their mouth; these are the fruits that expose the hidden wolf. People living in openly and obviously sinful lifestyles certainly should also be rejected as prophets and teachers, but there is no subtly or secrecy to that kind of perversion. The most deadly wolf, the one against which we are so carefully warned, is the one who looks like a sheep. We spot him by the content of His teaching, which means we must know the truth ourselves and be careful to listen to the words that professing Christian leaders are saying. As Paul said:

"But even if we or an angel from heaven should proclaim to you a gospel contrary to what we proclaimed to you, let that one be accursed! As we have said before, so now I repeat, if anyone proclaims to you a gospel contrary to what you received, let that one be accursed!" (Galatians 1:8-9).

This has always been the test of the true and false prophet. As God spoke through Moses:

"If a prophet or a dreamer of dreams arises among you and gives you a sign or a wonder, and the sign or the wonder comes true, concerning which he spoke to you, saying, ‘Let us go after other gods (whom you have not known) and let us serve them,’ you shall not listen to the words of that prophet or that dreamer of dreams; for the Lord your God is testing you to find out if you love the Lord your God with all your heart and with all your soul. You shall follow the Lord your God and fear Him; and you shall keep His commandments, listen to His voice, serve Him, and cling to Him. But that prophet or that dreamer of dreams shall be put to death, because he has counseled rebellion against the Lord your God who brought you from the land of Egypt and redeemed you from the house of slavery, to seduce you from the way in which the Lord your God commanded you to walk. So you shall purge the evil from among you," (Deuteronomy 13:1-5).

And also:

"But the prophet who speaks a word presumptuously in My name which I have not commanded him to speak, or which he speaks in the name of other gods, that prophet shall die.’ You may say in your heart, ‘How will we know the word which the Lord has not spoken?’ When a prophet speaks in the name of the Lord, if the thing does not come about or come true, that is the thing which the Lord has not spoken. The prophet has spoken it presumptuously; you shall not be afraid of him," (Deuteronomy 18:20-22).

The Prophet who says things in God's name that are untrue or predicts things in the LORD's name that don't happen is a false prophet. The Prophet who leads us away from the true, biblical God is a false Prophet. The content of their words is what gives them away. We know them by their fruit.

This is certainly what the earliest Churches understood Jesus to mean. In one of the earliest Christian writings outside the New Testament, we read:

"Whosoever, therefore, shall come and teach you all these things that have been said before, receive him; but if the teacher himself be perverted and teach a different doctrine to the destruction thereof, hear him not.," (Didache, Chapter 11).

Likewise in another ancient Christian writing, we find:

"Every one that teaches anything beyond what is commanded, though he be [deemed] worthy of credit, though he be in the habit of fasting, though he live in continence, though he work miracles, though he have the gift of prophecy, let him be in thy sight as a wolf in sheep’s clothing," (Pseudo-Ignatius, Epistle to Hero the Deacon, Chapter 2).1

And Tertullian, the early Latin Theologian, wrote:

"But let us rather be mindful of the sayings of the Lord, and of the letters of the apostles; for they have both told us beforehand that there shall be heresies, and have given us, in anticipation, warnings to avoid them; and inasmuch as we are not alarmed because they exist, so we ought not to wonder that they are capable of doing that, on account of which they must be shunned. The Lord teaches us that many 'ravening wolves shall come in sheep’s clothing.' Now, what are these sheep’s clothing’s, but the external surface of the Christian profession? Who are the ravening wolves but those deceitful senses and spirits which are lurking within to waste the flock of Christ? Who are the false prophets but deceptive predictors of the future? Who are the false apostles but the preachers of a spurious gospel?" (Tertullian, The Prescription Against Heretics, Chapter 4).

We must, therefore, be on guard. We must be devoted to the Scriptures, to the gospel, and to the Lord. We must not be deceived by outward appearances of righteousness, not by novel and intriguing new ideas and practices, not even by what appear to be powerful miracles and prophetic insights. We must hold fast to the good news of Jesus Christ and the plain teachings of scripture. Jesus thought this was important enough to warn us about. The Apostles and Prophets echoed it. Let's regard it as important enough to keep ever before our minds, lest we be led astray. Our Lord graciously warned us in advance. Look at the fruit.


Inside the Bible

Jesus said
Matthew 7:22-23, "Many will say to Me on that day, ‘Lord, Lord, did we not prophesy in Your name, and in Your name cast out demons, and in Your name perform many miracles?’ And then I will declare to them, ‘I never knew you; depart from Me, you who practice lawlessness.’"

Paul said
1 Timothy 4:1, "But the Spirit explicitly says that in later times some will fall away from the faith, paying attention to deceitful spirits and doctrines of demons."

The Author to the Hebrews said
Hebrews 13:8-9, "Jesus Christ is the same yesterday and today and forever. Do not be carried away by varied and strange teachings."

Jude said
Jude 17-21, "But you, beloved, ought to remember the words that were spoken beforehand by the apostles of our Lord Jesus Christ, that they were saying to you, 'In the last time there will be mockers, following after their own ungodly lusts.' These are the ones who cause divisions, worldly-minded, devoid of the Spirit. But you, beloved, building yourselves up on your most holy faith, praying in the Holy Spirit, keep yourselves in the love of God, waiting anxiously for the mercy of our Lord Jesus Christ to eternal life."

Inside CARM

How do you identify a false teacher?
We can identify a false teacher or a false prophet by examining first and foremost their teaching and secondly their behavior in light of Scripture. If what they are teaching is not consistent with what the Holy Spirit has plainly revealed in Scripture, they are a false teacher and are to be ignored, even if they live extraordinary lives, even if they appear to have supernatural insight, or even if they seem to work great miracles.

How do you protect your family against false teachers?
It is difficult to be a people of truth in a world of falsehood, and it is right for a man to be concerned not only for himself but also for his wife and children. The Bible does not leave us to wander in the dark, however. There are some basic steps that we can take to guard our children in their youth and to prepare them to stand firm in maturity as they grow up and leave our homes.


  • 1. While the letter is falsely attributed to Ignatius of Antioch in the manuscripts we possess, its true author is unknown. We do know it was composed sometime between the 3rd-6th centuries and so it still demonstrates an early understanding of Jesus' words in Matthew 7 as a warning against false teachings of one whose outward behavior may seems upright.