Despite whatever you may think, the fact is that the issue never was whether you could support your position that fornication was wrong, but how atheism consistently determining sin, that without a transcendent moral standard that defines sin, in atheism your argument is only that, as another atheist can disagree with you that fornication is wrong, or gay marriage, etc.
Atheism is like a country without a substantive universal constitution, and under it what seems reasonable to Mao or atheistic Communism can just be easily justified as like Islamic conquests can.
Refute the logic, or give up.
Sheer nonsense.
Simply put, you sacrifice logic to propound your hang-up with labels.
Take for example your own wonderful (and hilarious, BTW) demonstration of this stupidity when you imply you don’t dispute that I could argue that fornication was wrong without invoking superstition / deity and then go on to say that (after obviously being distracted by labels), “atheism” determines “sin” arbitrarily. What else was my point in showing how fornication was wrong (using logical arguments and not superstition)?!
Apparently you aren’t able to make your own mind up on whether what you deem as “ought to do” requires supernatural, superstitious hoopla or not.