5 If then it was “the likeness of flesh of sin,” not flesh of sin, how, “That by sin He might condemn sin in the flesh”? So a likeness is wont to receive the name of that thing of which it is a likeness. The word man is used for a real man; but if you show a man painted on the wall, and enquire what it is, it is answered, “A man.” So then Flesh having the likeness of flesh of sin, that it might be a sacrifice for sin, is called “sin.” The same Apostle says in another place, “He made Him to be sin for us, who knew no sin.” “Him who knew no sin:” Who is He who knew no sin, but He That said, “Behold the prince of the world comes, and shall find nothing in me? Him who knew no sin, made He sin for us;” even Christ Himself, who knew no sin, God made sin for us.
What does this mean, Brethren? If it were said, “He made sin upon Him,” or, “He made Him to have sin;” it would seem intolerable; how do we tolerate what is said, “He made Him sin,” that Christ Himself should be sin? They who are acquainted with the Scriptures of the Old Testament recognise what I am saying. For it is not an expression once used, but repeatedly, very constantly, sacrifices for sins are called “sins.” A goat, for instance, was offered for sin, a ram, anything; the victim itself which was offered for sin was called “sin.”
A sacrifice for sin then was called “sin;” so that in one place the Law says, “That the Priests are to lay their hands upon the sin.” “Him” then, “who knew no sin, He made sin for us;” that is, “He was made a sacrifice for sin.” Sin was offered, and sin was cancelled. The Blood of the Redeemer was shed, and the debtor's bond was cancelled. This is the “Blood, That was shed for many for the remission of sins.”
Source: Sermons on Selected Lessons of the New Testament (New Advent)