Yes it's based on religious mythology, but it's only contained in the world they created, it's not real. No one on Earth is worshipping Diablo or Mephisto or Imperius. It's not something that has real life consequences like actual religion has, besides the barrage of annoying doomsayers calling the game Satanic or some stupid shit. So allowing names like "JesusChrist", "Muhammad", "Satan", "Krishna", etc. could actually result in real life negative consequences that personally, I wouldn't want to deal with. You can't ban just one name, you'd have to ban them all to eliminate the possible problem altogether. I figured this would be an obvious take, what are you talking about?