“Beware of false prophets who come disguised as harmless sheep but are really vicious wolves. You can identify them by their fruit, that is, by the way they act. Can you pick grapes from thornbushes, or figs from thistles? A good tree produces good fruit, and a bad tree produces bad fruit. A good tree can’t produce bad fruit, and a bad tree can’t produce good fruit. So every tree that does not produce good fruit is chopped down and thrown into the fire. Yes, just as you can identify a tree by its fruit, so you can identify people by their actions.
“Not everyone who calls out to me, ‘Lord! Lord!’ will enter the Kingdom of Heaven. Only those who actually do the will of my Father in heaven will enter. On judgment day many will say to me, ‘Lord! Lord! We prophesied in your name and cast out demons in your name and performed many miracles in your name.’ But I will reply, ‘I never knew you. Get away from me, you who break God’s laws.’” (Matthew 7:15-23)
False prophets were common in Old Testament times. They prophesied only what the king and the people wanted to hear, claiming they spoke for God. But they failed to speak the truth, and their predictions did come to pass.
False teachers are just as common today. Jesus says to beware of those whose words sound religious but who are motivated by money, fame, or power. You can tell who they are because in their teaching they minimize Christ and glorify themselves. We should evaluate teachers’ words by examining their lives. Just as trees are consistent in the kind of fruit they produce, good teachers consistently exhibit good behavior and high moral character as they attempt to live out the truths of Scripture. This does not mean we should have witch hunts, throwing out church and school teachers, pastors, and others who are less than perfect. Every one of us is subject to sin, and we can show the same mercy to others that we need for ourselves. When Jesus talks about “bad trees,” he means teachers who deliberately teach false doctrine. We must examine the teachers’ motives, the direction they are taking, and the results they are seeking.
The best way to be on your guard against false teaching is to know what’s true. You might do a Scripture study on truth. The Gospel of John is a good place to start: John 8:12; 14:6; 17:17.