For what the law could not do, in that it was weak through the flesh, God sending his own Son in the likeness of sinful flesh, and for sin, condemned sin in the flesh:
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Augustine of Hippo
AD 430
Here Paul clearly teaches that the precepts of the law were not fulfilled (though they should have been) because those who had the law before grace were given over to worldly goods, from which they were trying to get happiness. Nor did they have any fear except when adversity threatened these goods, and when that happened they easily withdrew from the precepts of the law. Therefore the law grew weaker as its commands went unheeded. This was not the fault of the law but came about through the flesh, because those who went after worldly goods did not love the righteousness of the law but put temporal advantage ahead of it. And so our deliverer, the Lord Jesus Christ, took on mortal flesh and came in the likeness of the flesh of sin. For death is the reward due to the flesh of sin. Of course the Lord’s death was voluntary and not something which he owed. Yet nevertheless the apostle calls the assumption of mortal flesh “sin” even if it was sinless, because when the Savior died he was made sin, so to speak. But “he condemned sin in the flesh,” for the Lord’s death ensured that death would not be dreaded, that worldly goods would not be sought and that worldly evils would not be feared by those who had previously been wise in the ways of the world and thus unable to fulfill the commands of the law.