Theá had been running around the town for the entire time she was fighting, checking for any survivors. The only living ponies she found were cultists. They attacked her, and she retaliated. Old Hoof was abandoned and infested with nothing but undead and cultists, so she didn't kill innocents. I have no justification for Crashing or Torrential, but let's just say that there's this whole "wrath of God" thing going on. When they get mad it's off the scale. 

So, of the three you have listed, the only mortals Theá has killed attacked her first. She adopts the philosophy of the predator, that she kills for two reasons: To protect, or to feed, and I've stuck with that. It's for the same reason that she doesn't just impale Scalpel, because she's not sure of his guilt yet. She suspects, yes, but unless she's sure she won't do anything. 

But, still, they're Gods. The individual pony, or a few hundreds of them, means very little in the grand scheme of things. I honestly don't think they're all that different from the Christian gods, nor even the gods of any religion. Also, the whole personality thing... Well, we do have that "Divine Flaw" thing :P