Sin is doing what we know is wrong intentionally. We learn the Commandments, we learn the law of love taught to us by Jesus in the NT, we read the Bible, the Beatitudes, so we can learn what is wrong and what is right. Jesus brought us salvation by His sacrifice. We still have a responsibility to learn what is right and do it.
"Sin is doing what we know is wrong intentionally."
Actually, the Bible points out that sin can be unintenetional, as well.
Regards