“Beware of false prophets, who come to you in sheep’s clothing, but inwardly are ravenous wolves. You will know them by their fruits. Do me gather grapes from thornbushes or figs from thistles? Even so, every good tree bears good fruit, but a bad tree bears bad fruit. A good tree cannot bear bad fruit, nor can a bad tree bear good fruit. Every tree that does not bear good fruit is cut down and thrown into the fire. Therefore, by their fruits you will know them.” (Matthew 7:15-20).

A false teacher may disguise himself. He may look harmless (cf. Matthew 23:25-28; 2 Corinthians 11:14). He may, to the undiscerning, look like and sound like one who is a sheep (a follower of the Shepherd).

How can one identify a false teacher? Jesus says that one may know “by their fruits.” As one can know whether a plant is a grapevine or thornbush by what is produced; and as one can know whether a plant is a fig tree or thistle by what is produced; even so, one can know the kind of teacher one is by observing the fruits produced. (Note, in the text “good” and “bad” does not mean varying qualities of the same type of fruit. This is speaking of different types of fruit, for example – grapes and thornbushes, figs and thistles.)

What does Jesus mean “by their fruits”? The following options have been suggested. (1) Some believe that this refers to the personal conduct of their lives. Fruit may refer to conduct (e.g. Matthew 3:8). (2) Some believe that this refers to their teaching. Fruit may refer to words (e.g. Matthew 12:33-37). (3) Some have suggested that this refers to the effect of their teaching (e.g. Matthew 23:15). (4) Some have suggested that the meaning is found in a combination of these options.

While there may be some value in observing all of these, it seems to me that option two best fits the context. Consider this comment by Thomas B. Warren, “In the view of this author, in the light of the fact that Jesus had just warned against false prophets (7:15), Jesus meant that false teachers can be identified by the doctrines which they teach. Many false teachers live good moral lives. They seem to be pious, to love God, to love their families, to love their neighbors, etc. Yet they teach false doctrine. It is because some false teachers have so many attributes which might well be praised that they can so easily deceive so many people” (Thomas Warren, Matthew 7, The Spiritual Sword Lectureship: The Book of Matthew, p. 269, editors Garland Elkins and Thomas B. Warren). If this is the meaning, then this would be a reminder of what had been taught in the Law and the Prophets (Deuteronomy 13:1-5; 18:20-22; Isaiah 8:20). Notice the test: (1) Does he teach another god? (2) Does he teach something which contradicts God’s word? (Note, it does not matter if he has provided some kind of sign or not. If it contradicts God’s word, then it is to be rejected). (3) Does he give prophecy which does not come to pass? (Note, even one false prophecy discredits the person as a prophet of God). These were ways that God told Israel that they could test a prophet.

We are to be discerning (1 John 4:1; Acts 17:11; 1 Thessalonians 5:21). We are to inspect the fruit.