St. Augustine said that Jesus was in His human nature like us in that He was:
- Posse pecarre- He could sin
- Posse non pecarre- He could also not sin
But, said the Saint, in His divine nature he was
Non posse pecarre- He could not sin because He was God and it was against His nature to do so.
The difference to us is that we are (again Augustine);
Non posse non pecarre- it is impossible for us not to sin because we are fallen.
OK, before we get into the “is man evil?” question again, all I am saying here is that in Augustines theology the fall is the paramount idea upon which the rest of his theology is formed. I mean, intially, he even professed to believe that unbaptized infants went to hell. He later revised his opinion to say it was a hell without suffering when people objected that his idea of God was too cruel. For Augustine, the lack of Christ’s having a fallen nature is what allowed Him to in His flesh be tempted in every way as we are and yet never sin because His flesh was not fallen and He also was divine, this was later affirmed by the Church when it declared Jesus two natures to be distinct but not sperate at the Council of Chalcedon.