A good tree cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit.
All Commentaries on Matthew 7:18 Go To Matthew 7
John Chrysostom
AD 407
And if He states the same thing twice, it is not tautology. But, lest any one should say, Though the evil tree bear evil fruit, it bears also good, and makes the distinction difficult, the crop being twofold: This is not so, says He, for it bears evil fruit only, and never can bear good: as indeed in the contrary case also.
What then? Is there no such thing as a good man becoming wicked? And the contrary again takes place, and life abounds with many such examples.
But Christ says not this, that for the wicked there is no way to change, or that the good cannot fall away, but that so long as he is living in wickedness, he will not be able to bear good fruit. For he may indeed change to virtue, being evil; but while continuing in wickedness, he will not bear good fruit.
What then? Did not David, being good, bear evil fruit? Not continuing good, but being changed; since, undoubtedly, had he remained always what he was, he would not have brought forth such fruit. For not surely while abiding in the habit of virtue, did he commit what he committed.
Now by these words He was also stopping the mouths of those who speak evil at random, and putting a bridle on the lips of all calumniators. I mean, whereas many suspect the good by reason of the bad, He by this saying has deprived them of all excuse. For you can not say, 'I am deceived and beguiled;' since I have given you exactly this way of distinguishing them by their works, having added the injunction to go to their actions, and not to confound all at random.
