Because the carnal mind is enmity against God: for it is not subject to the law of God, neither indeed can be.
Read Chapter 8
Augustine of Hippo
AD 430
Paul explains why he said “hostile” so that no one should think that there is some nature derived from an opposing principle which God did not create and which fights against him. An enemy of God is one who does not submit to his law and who behaves this way because of the wisdom of the flesh. This means that he seeks worldly goods and is afraid of worldly evils. The normal definition of wisdom is to seek what is good and avoid what is evil. Therefore the apostle is right to describe the wisdom of the flesh as the longing for “goods” which do not remain with a man and when there is a fear for losing those things which one day will have to be left behind anyway. Wisdom of this kind cannot submit to the law of God. It must be destroyed so that the wisdom of the Spirit, which does not place its hope in worldly goods nor is afraid of worldly evils, may take its place. For the one nature of the soul has both the wisdom of the flesh when it follows lower things and the wisdom of the Spirit w...
Paul is not saying that it is impossible for a wicked person to become good but rather that it is impossible for one who continues in wickedness to be subject to God. For a person to change and become good and subject to God is easy…. If we give our souls up to the Spirit and persuade our flesh to recognize its proper position, we shall make our souls spiritual as well. But if we are lazy we shall make our souls carnal. For since it was not natural necessity which put the gift into us but freedom of choice, it now rests with us which way we shall choose to go.
In the preceding section [n. 612] the Apostle had presupposed that the prudence of the flesh is death, and here he intends to prove this. And first, he proves it; 308 secondly, he shows that the believers to whom he writes are immune to such prudence, there [v. 9; n. 625] at But you are not in the flesh. In regard to the first he does two things. First, he proves his statement about prudence of the flesh in the abstract; secondly, he applies what he had said about prudence of the flesh to those who follow prudence of the flesh, there [v. 8; n. 624] at And those who are in the flesh. In regard to the first he sets out three middle [terms], each of which proves the one before it. 620. Using the first middle, he proves something stated earlier [n. 617], namely, that the prudence of the flesh is death, in the following way: He that is hostile to God incurs death: "But as for those enemies of mine, who did not want me to reign over them, bring them here and slay them before me" (Lk 19:27); ...
