Just as we have borne the image of the man of dust, we shall also bear the image of the man of heaven. I tell you this, brethren: flesh and blood cannot inherit the kingdom of God, nor does the perishable inherit the imperishable (1 Corinthians 15:49-50).
Here Paul concludes with how we ought to be specially conformed to the man, that is to say, the heavenly man.
We can be conformed to the heavenly man in life in two ways, namely, of grace and of glory, and the one is the way to the other, because without the life of grace we cannot attain to the life of glory.
[...] Therefore, so that we might be of heaven, i.e., attain to the life of glory, let us bear the image of the man of heaven, by the life of grace: “Those whom he foreknew he also predestined to be conformed to the image of his Son” (Rom. 8:29).
And so we ought to be conformed to the man of heaven in the life of grace, because otherwise we will not attain to the life of glory.
And this is what he says: I tell you this, brethren; as if to say: unless you live, namely, the life of grace, you cannot attain to the kingdom of God, i.e., to the life of glory, because flesh and blood cannot inherit the kingdom of God.
[...] We must not think that by flesh and blood, he means that the substance of the flesh and blood cannot inherit the kingdom of God, but rather flesh and blood, i.e., those devoting themselves to flesh and blood, namely, men given to vices and lusts, cannot inherit the kingdom of God.
And thus is flesh understood, i.e., a man living by the flesh: “But you are not in the flesh, you are in the Spirit, if in fact the Spirit of God dwells in you” (Rom. 8:9).
[...] Or: flesh and blood, i.e., the corruption of flesh and blood cannot inherit the kingdom of God; that is, after the resurrection, the body will not be subject to the corruption of flesh and blood, as it is of the man who lives now.
Therefore and accordingly, he adds, nor does the corruptible inherit incorruption, i.e., nor can the corruption of mortality, which is expressed here by the term “flesh,” inherit incorruption, i.e., the incorruptible kingdom of God, because we will rise in glory:
“Because the creation itself will be set free from its bondage to decay and obtain the glorious liberty of the children of God” (Rom. 8:21).
Thomas Aquinas (1225-1274): Commentary on 1 Corinthians, cap. 15, lect.7, 998-1000.
