14 Therefore, my beloved, we also have received of the Spirit of Christ, and Christ dwells in us, as it is written that the Spirit said this through the mouth of the Prophet:— I will dwell in them and will walk in them. Therefore let us prepare our temples for the Spirit of Christ, and let us not grieve it that it may not depart from us. Remember the warning that the Apostle gives us:— Grieve not the Holy Spirit whereby you have been sealed unto the day of redemption. For from baptism do we receive the Spirit of Christ.
For in that hour in which the priests invoke the Spirit, the heavens open and it descends and moves upon the waters. And those that are baptized are clothed in it; for the Spirit stays aloof from all that are born of the flesh, until they come to the new birth by water, and then they receive the Holy Spirit. For in the first birth they are born with an animal souls which is created within man and is not thereafter subject to death, as he said:— Adam became a living soul. But in the second birth, that through baptism, they received the Holy Spirit from a particle of the Godhead, and it is not again subject to death.
For when men die, the animal spirit is buried with the body, and sense is taken away from it, but the heavenly spirit that they receive goes according to its nature to Christ. And both these the Apostle has made known, for he said:— The body is buried in animal wise, and rises again in spiritual wise. The Spirit goes back again to Christ according to its nature, for the Apostle said again:— When we shall depart from the body we shall be with our Lord. For the Spirit of Christ, which the spiritual receive, goes to our Lord.
And the animal spirit is buried in its nature, and sense is taken away from it. Whosoever guards the Spirit of Christ in purity, when it returns to Christ it thus addresses him:— “The body into which I went, and which put me on from the water of the baptism, has kept me in holiness.” And the Holy Spirit will be earnest with Christ for the resurrection of that body which kept Him with purity, and the Spirit will request to be again conjoined to it that that body may rise up in glory.
And whatever man there is that receives the Spirit from the water (of baptism) and grieves it, it departs from him until he dies, and returns according to its nature to Christ, and accuses that man of having grieved it. And when the time of the final consummation shall have come, and the time of the Resurrection shall have approached, the Holy Spirit, that was kept in purity, receives great power from its nature and comes before Christ and stands at the door of the tombs, where the men are buried that kept it in purity, and awaits the (resurrection) shout.
And when the Watchers shall have opened the doors of heaven before the King, then the cornet shall summon, and the trumpets shall sound, and the Spirit that waits for the (resurrection) shout shall hear, and quickly shall open the tombs, and raise up the bodies and whatsoever was buried in them, and shall put on the glory that comes with it. And (the Spirit) shall be within for the resurrection of the body, and the glory shall be without for the adornment of the body. And the animal spirit shall be swallowed up in the heavenly Spirit, and the whole man shall become spiritual, since his body is possessed by it (the Spirit).
And death shall be swallowed up in life, and body shall be swallowed up in Spirit. And by the power of the Spirit, that man shall fly up to meet the King and He shall receive him with joy, and Christ shall give thanks for the body that has kept His Spirit in purity.
Source: Demonstrations (New Advent)