a Do men gather grapes of thorns,
a Or figs of thistles?
b Even so every good tree brings forth good fruit,
c But the corrupt tree brings forth evil fruit.
d A good tree cannot bring forth evil fruit,
c Neither can a corrupt tree bring forth good fruit.
b Every tree which does not bring forth good fruit,
b Is hewn down, and cast into the fire.
a Therefore by their fruits you will know them.
Jesus then emphasises the kind that He is speaking about. They reveal their falseness by their lives and by their teaching. Thus they are not only like wolves dressed up as sheep, they are like thorns which give the impression of bearing grapes, or thistles which give the impression of bearing figs. They put up a great pretence and make a great show and seem to be offering so much. But on a closer look it is seen to be a sham. They offer much, only in the end to bring disappointment and even discomfort. From a distance the small black berries of the buckthorn can look like grapes, and certain spiky bushes can give the impression of bearing figs. But Jesus' point is that once people get closer instead of gathering fruit, all they gather is thorns in their hands. The fruit of the bushes will reveal them for what they are. The same description of thorns and thistles is found in Genesis 3:18 (the same Greek words are used in LXX). Possibly Jesus therefore expects His hearers here to remember the Garden of Eden and gather from it whose influence lies behind these false teachers (compare 2 Corinthians 11:13-15).
Jesus then turns their attention to trees. All agriculturalists know the difference between a good and a bad tree. One produces good, healthy fruit. The other produces fruit of a kind, but it is not pleasant to eat, because there is something wrong with the tree (compare Isaiah 5:1-7). However carefully nurtured it has been, it has turned out to be ‘corrupt'. And it will never produce good fruit. So the sensible tree farmer cuts it down so that it will cease taking the goodness from the ground, and then he burns it. He uses it for what it is good for, fuel. And then it is gone. In the same way false teachers will be known by their fruit, whether it be the fruit of false doctrine or the fruit of false motives. And they must recognise that one day they too will be ‘burned'.
But Jesus' carefully selected words bring out the fuller truth. Because the tree was ‘corrupt' and therefore ‘useless for its real purpose' it produced ‘evil (poneros) fruit'. The application has become a part of the illustration. The evil that comes forth from it reveals the evil that is in its heart (Matthew 15:11; Mark 7:15; Mark 7:20-23). Here ‘evil' has its deepest meaning of something so hateful in the sight of God that it is rejected (contrast the use in Matthew 7:11 where the idea was of a root of sin in man that could be dealt with in mercy). Like the broad way it leads to destruction.
For Matthew 7:19 compare Matthew 3:10. Jesus may well have heard these words on John's lips, and here He confirms His full agreement with them. But Jesus greater detail confirms that we have here genuine teaching of Jesus.