PvP: Don't we just love it!

[Madeiner]

I agree with all the above, and if the DM does not want PvP, to just say, in addition to what has been said before:

If PvP happens, and somebody dies, then all the characters involved must be retired and those still alive become NPCs.
I guess the priest player will then find a lot of reasons to not kill the other character, and it will also prevent ganging up on the new guy (not involved = not retired)

I still believe other solutions are better.