I want you eat from that one especially. Indeed, I command it. For the moment you eat from it you will be able to judge for yourselves what is good and what is bad. But God has not said this. God makes law for man.
Man participates in it.
Man does not establish law for himself. I know I have spent a lot of time on this paragraph, but it contains certain key concepts that are important to what follows. You will find many books and teachers that deal with conscience and sin, that quote Vatican II and John Paul II, and that in may ways look orthodox.