1 Corinthians 15:45 (ESV)

45 Thus it is written, “The first man Adam became a living being”; the last Adam became a life-giving spirit.

Paul is still discussing the difference between the natural and the spiritual body (1 Corinthians 15:44). He refers to Genesis 2:7, where it is said that God breathed into Adam’s nostrils the breath of life, and he became a living creature (or, a living soul).

In the Septuagint, which Paul is loosely quoting from, the Greek word psuché is used. It is related to the word psuchikos (natural), which Paul has just used in 1 Corinthians 15:44.

From Genesis 2:7 Paul moves on to a statement of his own: The last Adam became a life-giving spirit. With the last Adam he is referring, of course, to Jesus Christ. It is not that living creature and life-giving spirit are complete opposites. Rather, Paul is moving from the lesser to the greater. This technique is employed more than once in the New Testament (see, for example, John 1:17 and Hebrews 9:13–14.)

As in 1 Corinthians 15:44, Paul is moving from the natural (psuché) to the spiritual (pneuma). As modern readers we are quick to associate the natural with what is visible and material, and spirit with what is invisible and immaterial. This, however, is not how Paul uses these words. After all, he has just spoken of a spiritual body (1 Corinthians 15:44). By calling Christ spirit, he is probably emphasizing the Spirit’s work in giving Christ his new, glorified body (compare Romans 8:11).

Christ did not always have a spiritual body. He was born with a natural body and experienced all the weaknesses of such a body (Hebrews 2:14–18; Hebrews 4:15). It is with his resurrection that he “became a life-giving spirit.”  

There was continuity between Christ’s spiritual body and his old, natural body. People could recognize him. The nail scars were even visible on his hands. Yet he was no longer subject to death or to any form of pain or difficulty. It also seems as if his body was no longer subject to laws of time and space. He came and went as he wished, moving even through locked doors (John 20:19–29). Christ ascended to heaven and is now dwelling there with his body. His body, being a spiritual body, is suited for heaven.

After Paul has stated that Adam “became a living being (psuché),” we would expect him to say that Christ “became a living spirit (pneuma).” Instead he writes that Christ “became a life-giving spirit.” In this way he emphasizes that Christ shares his life with his followers.