How could Jesus bear all the sins of the human race on the cross without becoming a sinner?
Jesus bore the sins of the human race as a substitute, not by becoming a sinner. He took the sinner's place, just as the ram provided for Abraham became the substitute for Isaac without becoming Isaac. Scripture says He took all sins upon Himself yet remained without sin.
Les explains that II Corinthians 5 says He became sin for us, He who knew no sin, that we might have the righteousness of Christ in Him. Yet He did not become a sinner per se; He took the sinner's place and became our substitute. Les uses Abraham offering Isaac as an example: God provided a ram in the thicket, and the ram became the substitute. The ram did not become Isaac, but it became the substitute. In the same way, when Christ went to the cross, He did not become a vile sinner, but He took upon Himself all the sins of the human race without becoming a sinner, and Scripture says He was yet without sin. This is beyond human comprehension, but it was His substitutionary work: where you and I should have died, He took our place. He did not become another person; He merely became our substitute. Les says Paul refers to this in Philippians chapter 2 as well as in Galatians 2.
For he hath made him to be sin for us, who knew no sin; that we might be made the righteousness of God in him.
For we have not an high priest which cannot be touched with the feeling of our infirmities; but was in all points tempted like as we are, yet without sin.