Wait, I didn’t see what you are responding to but in itself how can judging others be a sin? God tells us all kinds of things in the Bible that are sinful and which we should stay away from He also gives us reasoning and the ability to see right from wrong so how can we just go “blind” and not judge anything? Further, let’s just get rid of the courts then cause how can a judge or jury of peers judge someone’s deeds after all?
Because the Bible tells us so.