Finally, there is the test of good works, which is the test that Jesus Himself gives in this sermon. He repeats it twice, once at the beginning of this section, and once at the end. In between he illustrates what he is saying. “Ye shall know them by their fruits… by their fruits ye shall know them” (vv. 18, 20). He shows that men are like fruit trees. Good ones only produce good fruit, and bad ones only produce fruit that is bad.
This means two things. First, it means that there must be fruit if the so-called Christian life is genuine. On the one hand, it is certainly wrong to teach that salvation comes by works. Salvation is by grace through faith, which is what Paul defends in the book of Galatians. However, it is equally wrong to imply that salvation can be real without good works. It is true that salvation may not produce good works as fast as we would like to see them. They may not appear in the same terms that we are accustomed to seeing them. Nevertheless, there must be good works. The evidence of good works or the absence of them can be a very good test of false doctrine.
The second point is that there must be satisfying fruit. This means that it must be spiritual fruit and not just the good works of which the world is capable. To put it practically we may ask this, “Does the teaching really strengthen and encourage the hearer? Is it matched by blessing and true Christian character in the life of the teacher?”
This is suggested quite clearly by the meaning Christ words must have had for those who heard them originally. For they must have related His words about grapes from thorns and figs from thistles to plants they knew personally. On this point William Barclay writes,
There was a certain thorn, the buckthorn, which had little black berries which closely resembled little grapes… And there was a certain thistle which had a flower which, at least at a distance, might well be taken for a fig. The point is real, and relevant, and salutary. There may be a superficial resemblance between the true and the false prophet. The false prophet may wear the right clothes and use the right language, but you cannot sustain life with the berries of a buckthorn or the flowers of a thistle; and the life of the soul can never be sustained with the food which a false prophet offers. The real test of any teaching is this: Does it strengthen a man to bear the burdens of life, and to walk in the way wherein he ought to go?1
If we put these three things together—whether or not there is a strait gate in the message, whether or not the unpleasant themes of sin and judgment are dealt with along with the message of God’s great love and grace, and whether or not there is real and satisfying fruit as a result of such teaching—then we have a way of discerning truth from falsehood and of giving attention only to that message that comes from the Lord. If you are a Christian, God wants you to use those principles to discern true teaching and to use it so that you might grow spiritually. If you are not yet a Christian, Jesus invites you to use these standards to evaluate all religious teaching.
1William Barclay, The Gospel of Matthew (Philadelphia, PA: Westminster, 1958), vol. 1, 288.
