Even though some people hope they are not marring the beauty of Christ when they say He could have sinned, Christ’s reputation is definitely diminished by this erroneous teaching. For example, if Christ could have sinned while He was on earth, why could He not sin in heaven today? People who say that Christ could have sinned on earth sometimes recognize the seriousness of the implication that Christ could sin in heaven today, and so they try to resolve this problem by stating either that Christ’s glorified body keeps Him from sinning today, or else that Christ defeated Satan at the Cross and is no longer tempted by him, or else that Christ became humanly impeccable after a human victory over sin in the wilderness.
However, a glorified body is no guarantee of impeccability at all, because Lucifer once lived in heaven with a glorified body free of a sin nature, and yet he sinned in spite of all this. The reason Christ is impeccably holy today is the same reason He has always been impeccably holy—Christ is eternally God, and God can never sin.
To say that Christ is impeccable in heaven today only because He defeated Satan and is no longer tempted by him is to overlook a very important fact: Christ (along with the Father and the Spirit) is still tempted by wayward people on earth! First Corinthians 10:9 tells us:
We should not test [an even stronger Greek word for tempting than is used in James 1:13 and Hebrews 3:9] the Lord, as some of them did, and were killed by snakes.
The reason Christ remains impeccably holy even in the face of all our testings of Him today is the same reason that He has always been impeccably holy—Christ is eternally God, and God can never sin.