Matthew 7:15-23 By Their Fruit You Will Know If They Are Known.
The Law and the prophets gave several criteria by which to test the prophets, whether they were true or false. If what they predicted did not come to pass even once, they were false. If they were able to perform signs and wonders, but the god they worshipped was not the LORD, they were false. Most importantly, if what they taught was contrary to the Law and the rest of the Scriptures, the canonical/hermeneutical test, they were false. All of these tests shared the same basic principle, which Jesus reiterates here. A true prophet’s character, seen in word and deed, is one which is in harmony with the Scriptures.
No one is perfect, but perfection for saints is also seen in repentance when they go wrong. False prophets actually make an effort to appear genuine – wolves in sheep’s clothing, but their intent is to devour the sheep (v. 15; Jer. 26:16; Mic. 3:5). One can no more get good fruit from a false prophet than one can get edible fruit, signs and products of covenantal blessing, from thorn bushes and thistles, the signs and products of covenantal cursing (Mt. 7:20; 12:33; Lk. 6:43). As in the broad way that leads to destruction (vv. 13-14), false prophets and those who follow them, will be thrown into the fire. “Therefore by their fruits you will know them” (v. 20 Cf. Mt. 12:33; Jn. 15:2, 6).
Words are not enough. Anyone can say that they are a Christian, especially if it is not true. The question is whether one does the will of the Father in heaven. Again, it does not matter whether one has prophesied, cast out demons, or performed any other wonders, if they practice lawlessness, meaning that it is the accepted course of their lives to live contrary to God’s law. The crux of the matter is not a person’s claim to know Jesus, but whether he has ever known them, for salvation is based first and foremost on Jesus knowing us first, for only then can we know him. Many will hear, “I never knew you” (v. 23).