Tying up some loose ends from last week. But there is much more to come on this subject
1 Although the bodies of the risen are to be the same in species as our bodies are now, they will have a different disposition.
2 First, to be sure, in this respect: All the bodies of those who rise, both the good and the evil, will be incorruptible.
3 And the reason for this is threefold.
4 One reason is taken from the very purpose of the resurrection. For both the good and the evil will rise for this: that in their very own bodies they may receive their reward or their punishment for the deeds they performed while they lived in the body. But the reward of the good, felicity, that is, will be everlasting; in like fashion, too, everlasting punishment is due to mortal sin. Each of these points was established in Book III. Necessarily, then, in each case an incorruptible body must be assumed.
5 The second reason is taken from the formal cause of those who rise which is the soul. We said above that, lest the soul remain forever separated from the body after the resurrection, the soul will once again assume the body. Since, then, this reception of the body is provided for the perfection of the soul, it is suitable that the disposition of the body be proportioned to that of the soul. But the soul is incorruptible. Hence, the body restored to the soul will be incorruptible.
6 The third reason can be found in the active cause of the resurrection. For God, who will restore the already corrupted bodies to life, will be able to grant this so much more firmly by preserving forever the life regained in them. And by way of example of this, when He chose He preserved even corruptible bodies from corruption unharmed, as He did the bodies of the three youths in the fiery furnace (see Daniel 3:93-94).
7 Thus, then, must one understand the incorruptibility of the state to come: that this body, corruptible now,, will be made incorruptible by the divine power, so that the soul will have perfect dominion over the body in the course of vivifying the body; nor will this communication of life be subject to any obstacle at all. Hence, also, the Apostle says: “This corruptible must put on incorruption, and this mortal must put on immortality” (1 Cor. 15:53).
8 Therefore, man when he rises will be immortal, not for this reason: he has assumed another body which is incorruptible (as the opinions mentioned held); but for this reason: This same body which now is corruptible will become incorruptible.
9 One must, therefore, understand the Apostle’s saying “Flesh and blood cannot possess the kingdom of God” (I Cor. 15:50) in this way: that the corruption of flesh and blood will be taken away in the state of the resurrection, while the substance of flesh and blood nevertheless persists. Hence, he adds: “neither shall corruption possess incorruption.”