The statement “you will know them by their fruit” (Matthew 7:16) is part of Jesus’ teaching about recognizing true followers and avoiding false prophets. Beginning with verse 15, we read this context: “Beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves. Ye shall know them by their fruits. Do men gather grapes of thorns, or figs of thistles? Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit. A good tree cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit. Every tree that bringeth not forth good fruit is hewn down, and cast into the fire. Wherefore by their fruits ye shall know them.” Matthew 7:15–20
In verses 21–23, Jesus makes a chilling announcement to many who assumed they belonged to Him. He warned them that on Judgment Day they will hear Him say, “Depart from me. I never knew you.” Just before that warning, Jesus had indicted those who pretended to follow Him but whose lives indicated something else. He told His followers that the “fruit” of their lives proved what was inside their hearts (cf. Mark 7:20–23).
Jesus gave the illustration of grape vines and fig trees. When we see grape vines, we expect them to contain grapes in season. We also expect fig trees to produce figs. A produce farmer who notices one of his fruit trees not bearing any fruit will cut it down. It is useless. Likewise, we would not come to a field of thistles and expect to harvest fruit. Thistles and thorn bushes can never produce fruit because of their nature. It is impossible. They have no capacity to produce anything but thorns (Matthew 12:33).
In our lives, every word and every action is fruit from our hearts. Sinners sin because that’s what is in their hearts. Thieves steal, rapists attack, and adulterers cheat because those sins are the fruit being produced from an evil heart. Bad hearts produce bad fruit. When Jesus said, “You will know them by their fruit” concerning false teachers, He was giving us a guide for identifying them. False prophets, speakers of lies, will have actions that correspond to their errant message. Just as their message is anti-God, so will be their works. They will stray from the path of righteousness.
When we repent of our sin and receive Jesus as Lord of our lives (John 1:12; Acts 2:38), He changes our hearts (2 Corinthians 5:17). Now the fruit that is produced is good fruit. Galatians 5:22 lists some of the fruit produced by a heart in tune with God. Our attitudes, actions, words, and perspectives change as we walk in fellowship with the Holy Spirit (1 John 1:6–7). When our hearts change, our fruit changes.
Many false prophets have come and gone, and many of them lived in blatant sin while preaching their message. Jim Jones openly engaged in adultery, drug use, and profanity. David Koresh had child “wives” as young as 11. False teachers might display the “fruit” of sexual immorality, greed, materialism, gluttony, and other sins while justifying their behavior and lifting themselves up as something holy. Unfortunately, many people through the years have been duped into following such characters and joining them in justifying the sin. “you will know them by their fruit.” No matter how good or convincing someone sounds, if he is bearing bad fruit, his message should be avoided.
Godly teachers will display good “fruit” such as making disciples (Matthew 28:19), using their gifts to benefit others (Romans 12:4–8), leading lost people to Christ (James 5:20), loving their fellow believers (1 John 3:14), and seeking humble ways to do good everywhere (Jeremiah 29:7). All of these things are indications of a good heart.
Often, people profess faith in Jesus as Savior, but it is a mere profession with no real faith. Some religious groups encourage baptism, confirmation, or other religious rites that are supposed to ensure one’s future in heaven. But as time goes on, the fruit being produced in such a life looks nothing like what is clearly prescribed in the Bible (1 Peter 1:16). Some attend church services but spend the rest of their time living entirely for themselves. Some may rise to prominence, even teaching or preaching, writing books, or dominating the media, but the fruit of their lives belies their words (Matthew 24:24). Greed, deception, immorality, pride, or dishonesty defines them, making them false prophets by Jesus’ standards (2 Peter 2:1–3).
While we can never know anyone else’s heart, we can make wise assessments about other people by observing the regular fruit of their lives. All of us stumble from time to time, and we may go through seasons of bearing little fruit (1 John 1:8). But 1 John 3:4–10 makes it clear that those who know God will not continue a lifestyle of bearing bad fruit. We have been transformed, and the fruit of our lives is evidence of that transformation. Apple trees don’t produce bananas, and strawberry plants don’t produce figs. This fact of nature is also true in the spiritual realm. We can identify those whose hearts have been redeemed by the fruit we see in their lives.