Messianic blogger James Pyles comments on whether it’s a sin to break God’s commandments in the Torah:
The whole "is it a sin if..." vs. "is it holy" issue is really the key and kind of a sad commentary. It's like saying "I only stay faithful to my wife because I might get caught" or "I only refrain from committing murder because of the police". If you choose to obey certain of the mitzvot, you do it out of love, not because you *have* to.