Did Jesus assume a sinful flesh when he became man?

No, when Jesus became man, he fully assumed a human nature, but came only in the likeness of sinful flesh (en homoiomati). Paul chose this wording in Romans 8:3 carefully because, while Jesus did indeed become like human beings (who now exist only with the corruption of their nature), he simultaneously constituted the great exception to a humanity that lives in sin. He is fully righteous and is led entirely by the Spirit of God. His incarnation as such is no humiliation, but his incarnation appears disgraceful in a world in which man has become synonymous with sin. Yet Jesus became man precisely because of that sin, in order to launch an assault upon sin even in its own domain and thereby ultimately rob it of its power.

Cranfield¹ objects to this traditional interpretation of the phrase, in the likeness of sinful flesh (Romans 8:3a). He follows Barth’s emphasis on the fact that Jesus did not assume human nature as it had been before the fall, but as it was at the time of his incarnation, long after the fall. However, since also remained God he is still much more than man in his fallen state. According to Cranfield, this is the reason why Paul employs the phrase likeness to, thereby indicating that Jesus is not completely subjected to human nature in its state after the fall, but he is much more than that. In effect, he argues that the word homooioma (likeness) applies exclusively to the word sarx (flesh). Paul is well aware that Jesus became man in the flesh only after the fall, and as such he can write that God condemns sin in the flesh (Romans 8:3b). However, in Romans 8:3a he is not merely writing about a likeness to the flesh, but a likeness to the sinful flesh. As such the word likeness cannot be restricted as applying only to the word sarx (flesh) without also applying to hamartia (sin). Jesus, in other words, shared in the weakness that characterizes human existence outside of paradise, yet without succumbing to sin (cf.²).