Mt 7:15-20
[Jesus said to his disciples,] 15“Beware of false prophets, who come to you in sheep’s clothing, but underneath are ravenous wolves. 16By their fruits you will know them. Do people pick grapes from thornbushes, or figs from thistles? 17Just so, every good tree bears good fruit, and a rotten tree bears bad fruit. 18A good tree cannot bear bad fruit, nor can a rotten tree bear good fruit. 19Every tree that does not bear good fruit will be cut down and thrown into the fire. 20So by their fruits you will know them.”
KNOWN BY THEIR FRUITS: In the beginning of creation, God caused the earth to bring forth every kind of plant that bears seed and every kind of fruit tree that bears fruit with its seed in it (Gn 1:12). In the mostly arid world of Palestine, trees enjoy a special status and are used for a variety of symbols. We find, for example, the tree of life and the tree of knowledge of good and evil in the Garden of Eden (Gn 2:9). Trees are a source of protective shade; to sit under a leafy tree is a symbol of security and rest. But, above all, trees provide fruits. Fruit trees that produce in their season (Ps 1:3) and do not cease to bear fruit (Jer 17:8) are an image of abundance.
In the Gospel, focus is given to fruit-bearing trees. By their fruits people judge trees to be good or not. But the image is directed to the “fruits” that people bear. Just as the nature of the fruit cannot be dissociated from the quality of the tree, so a person’s ethical conduct expresses who the person fundamentally is.
The rotten tree that bears bad fruit is applied by Matthew to the prophets of his time. They come in the guise of meek sheep, but the disciples will know them by their actions, by their “fruits.” The false prophets preach the easy way, which is contrary to the gospel teaching of the “narrow road.” They will not stress the hard way of the cross, the necessity of evangelical poverty, but will preach half-truths and misleading practices. If they ever preach the gospel, they will not practice it. If they ever teach the truth, they will not live it. They are dangerous because of their influence on unsuspecting believers who are led astray. Jesus warns us that by their fruits we will know the truth about them.