1. There is no parallel to this pericope in the other three Gospels. But the Scriptures have much to say about false teachers.
2. Jesus warns us not to have anything to do with a false teacher of religion. False teachers never come saying that their teaching is false. Satan never tells us who he is or what he is. He is the great liar and deceiver. False religious teachers look very innocent, like gentle sheep, but actually are vicious, like ravenous wolves.
3. Twice (vss. 16 and 20) our text says: "From their fruits you will recognize them." What is meant by fruits? Not their actions because we've already been told that their actions deceive us. Fruits here means "teachings". Whenever the Bible warns us about false teachers it warns us about their teachings. For example, I Jn. 4:1 says: "Beloved, do not believe every spirit but test the spirits to see whether they are of God because many false teachers have gone out into the world." Now read also vss. 2-3. How do you test the spirits? By determining what they teach about Christ, the Savior of the world. Except for the Muslims and Jews all teachers of religion claim to teach about Christ. But examine what they teach about Christ. Our text and all other texts like this one imply that we must first know the true teaching. You cannot determine who a false teacher is until you first know the true teaching.
4. Vs. 16 asks a simple question: "People don't gather grapes from thorns or figs from thistles, do they?" Of course they don't!! Thorns cannot produce grapes. Thistles cannot produce figs. Jesus means: "False teachers cannot produce good teaching."
5. Then, in vss. 17, 18 and 19 Jesus makes three observations to make the point very clear. This is a very serious matter. First, every beneficial tree bears good fruits and every useless tree bears bad fruits. There are no exceptions to this. Secondly, Jesus states the opposite: "A beneficial tree cannot bear worthless fruits nor can a useless tree produce good fruits." Thirdly, the judgement: "Every tree that does not produce good fruit is cut down and thrown into the fire." Jesus means that the false, deceiving teacher will lose his soul in hell. We think immediately of Elijah and the false prophets of Baal, I Kings 18:21-40. The prophets of Baal misled the Children of Israel into godlessness and sin. They were destroyed.
6. Think of how Satan appeared so innocently to Adam and Eve, Gen. 3. He was like an innocent sheep but inside like a ravenous wolf. Think of how Satan appeared to Jesus, Mt. 4:1-11, and attempted to mislead Him by using the Word of God. Think of Jesus' warning to his disciples at Matt. 24:4: "Beware lest anyone mislead you. Because many will come in My name saying: 'I am the Christ' and they will deceive many." False teachers always claim that they are of Christ.
7. When St. Paul was about to leave the pastors in Asia Minor, he said to them at Acts 20:29-31: "I know this, that after my departure, savage wolves will come in among you, not sparing the flock. Also from among yourselves men will rise up, speaking perverse things, to draw away the disciples after themselves. Therefore watch, and remember that for three years I did not cease to warn everyone night and day with tears." Again and again the Bible calls false teachers savage wolves which destroy the sheep. They come to Christians from the outside. They also arise in the church, in the congregations. It might happen in your family.
8. How do you prepare to combat false teachers in this dangerous world? Jesus said: "If you continue in My Word, then you are truly My disciples. And you will know the truth and the Truth will make you free." Jn. 8:31.32. St. Paul said: "Now I urge you, brethren, note those who cause divisions and offenses, contrary to the doctrine which you learned, and avoid them. For those who are such do not serve our Lord Jesus Christ, but their own belly, and by smooth words and flattering speech deceive the hearts of the simple." Rom. 16:17-18.
THEME: Why We Should Avoid False Teachers
II Jn. 10-11 reads: "If anyone comes to you and does not bring this doctrine, do not receive him into your house nor greet him; for he who greets him shares in his evil deeds." (Read vss. 7-9 for the meanings of "this doctrine"). Christians are warned many times in the Bible about the danger of false teachers.
I. THEY ARE TOTAL DECEIVERS, vs. 15
A. They are wolves in sheep's' clothing. Everyone knows immediately what this illustration means. It means that they look innocent but are deadly. God does not mingle wolves and sheep. We know the characteristics of both and know how to deal with both. God does not deceive us. But false teachers do deceive us. St. Paul used this very same illustration at Acts 20:29-31: "After my departure savage wolves will come in among you, not sparing the flock. Also from among yourselves men will rise up, speaking perverse things, to draw away the disciples after them". The deceivers might come from the outside or they might even arise from within the congregation. Think of Judas, the deceiver from within. Think of Arius, a pastor who lived at about 300 A.D. He very cunningly denied that Jesus Christ was true God. He was finally found out and deposed from office.
B. They are of Satan who is very cunning. St. Paul says at II Cor. 11:13-14: "For such are false apostles, deceitful workers, transforming themselves into apostles of Christ. And no wonder! For Satan himself transforms himself into an angel of light." False teachers are Satanic in their deception. Think of how Satan, the false teacher, deceived our first parents in Gen. 3. Think of how Satan tried to deceive Job and his friends. God permitted Satan to test Job. His friends interpreted that trial as caused by unrepented sin in Job. Think of how Satan tempted Jesus by twisting the Word of God, Mt. 4:1-11.
II. THEIR WORKS AND FRUITS ARE WORTHLESS AND DANGEROUS, vss. 16-20
A. Christians can distinguish these works and fruits. Lk. 11:28 tells us: "Blessed are those who hear the Word of God and observe it." His word is our armor both for offensive and defensive fighting the fight of faith, Eph. 6:10-17. Christians have the ability to distinguish true teaching from false teaching. I Jn. 4:1 tells us: "Beloved, do not believe every spirit but test the spirits to see whether they are of God because many false teachers have gone out into the world." Some Christians know Christian doctrine better than other Christians. But all Christians have a measure of knowledge to obey Jesus when He says: "Beware of false prophets."
B. Why the Works and Fruits of False Teachers Are Dangerous.
1. The illustrations. Why are people fearful of wolves? Because wolves destroy people. Why do people avoid rotten and useless fruits in the market? Because they are a waste of money and may cause disease.
2. The appIication. Vs. 19 of our text says: "Every tree which does not bear good fruit is cut down and cast into the fire." This means that all false teachers, unless they repent, will lose their souls in hell. The vs. following our text reads: "Not everyone who says 'Lord, Lord' will enter into the Kingdom of God but only the one who does the will of My Father in heaven." II Pet. 2:1 reads "But there were also false prophets among the people, even as there will be false teachers among you, who will secretly bring in destructive heresies, even denying the Lord who brought them, and bring on themselves swift destruction."
Our text is plain, simple and clear. We live in a dangerous world. Be faithful to your Lord.