Halfchan /his/ has serious problems that could be partly solved by IP range blocks. It doesn't have a big user base to begin with but such a board accompanies and potentially assists /pol/ in various ways so it would be nice to have.
However, ourchan moderation should make a decision ahead of time whether or not theological discussion should be allowed. I don't recommend it, because half the threads on the other /his/ are atheism vs theism bait threads and theological spam that belongs on a religion board. So as it stands, halfchan /his/ can't even focus on history and is constantly disrupted. If extended religious discussion (a totally separate thing from the history of religion) is allowed anywhere, it should be on a dedicated religion board /rel/ in my opinion.
A /his/ board should allow at a minimum the discussion of history, archaeology, genetics, linguistics, and anthropology. Opening the floor to the "humanities" should exclude religion but philosophy could be okay. The main issue is philosophical discussion potentially opens the door to the disruptive (a)theism bait threads. Maybe philosophy would be okay as long as that is explicitly banned along with theological debates. Otherwise philosophy would need to go to a /rel/ board.
If what I'm saying about religion sounds complicated or like a hassle, just remember history, archaeology, genetics, linguistics, and anthropology are all that's needed at a minimum. /rel/ isn't needed as badly as a simpler /his/.