Every tree that brings not forth good fruit is hewn down, and cast into the fire.
Read Chapter 7
Augustine of Hippo
On this point, one must carefully avoid the error of those who think that they find in these two trees a reason for believing that there are two natures and that one of them belongs to the nature of God but that the other neither belongs to God nor depends on him. This error has been rather fully discussed in other books, and if that is not sufficient it will receive still further treatment later. But we must now show that these two trees furnish no argument in support of it. First of all, in this similitude the Lord is speaking about two kinds of persons. This is so obvious that if anyone will but read the passages in the context of those that precede and follow it, he will be amazed at the blindness of those who would misinterpret it impersonally. Again, they fix their attention on the saying, “A good tree cannot bear bad fruit, nor can a bad tree bear good fruit,” and then they think that an evil soul cannot be changed into a better or a good soul into a worse. As though, in truth, ...
9. Then forasmuch as He had not commanded to punish, but only to beware of them, He, at once both to comfort those whom they vex, and to alarm and change them, set up as a bulwark against them the punishment they should receive at His hands.