Lighthouse said:It is not a sin when one is not under the law. Can a Christian transgress the law, Knight?
The first murder in the Bible was committed before the Law was given. It was not a righteous act, but a sinful one in light of God's holiness and the creation mandate of the sanctity of light.
You are misunderstanding the unchanging moral law of God (vs ceremonial law), how Jesus fulfilled it, and its relationship to believers. Sin is lawlessness. If a believer commits adultery, it is sin. Euphemizing it away or finding a 'not under the law' misunderstanding for a loop hole flies in the face of the weight of all of Scripture (OT and NT).