The Doctor and The Beast in “The Satan Pit”

If you are "the Beast", then answer me this - which one? Hmm? 'Cause the the universe has been busy since you've been gone. There's more religions than there are planets in the sky! The Arkiphets, Quoldonity, Christianity, Pash Pash, New Judaism, San Klah, Church of the Tin Vagabond - which Devil are you?

All of them.

What, then you're the truth behind the myth?

This one knows me, as I know him. The killer of his own kind.