On "open" Religion Forum threads posters may condemn deities, beliefs, religious authorities, practices, groups of believers, etc.
Posters who are offended by that town square type of debate should ignore "open" RF threads altogether and instead post to RF threads labeled "ecumenical" "caucus" "prayer" or "devotional."
That said, ad hominems say more about the poster than the object. I often remind RF posters that people do not use spit wads unless they run out of ammunition.
Ad hominems are also Logical Fallacies. The one of the receiving end would be justified in declaring a "win" on that basis and walking away from the debate.
I hope that will never be used to excuse anti-Semitism.
I note that no one likes to be attacked ad hominem. But everyone seems to enjoy attacking others that very way.
If the ethnic slurs used to describe rural American Fundamentalist Protestants by some FReepers were to be used of any other group, the poster would be banned as a bigot. It seems that on FR as in the main stream media, it's open season on Bubba.