Where is that in Origins?

Right at the start in the burning house.
At the top of the stairs if I remember right.

I have a hard time believeing that R.P.T. is a deity/angel/whatever worshiped by the cult. My explanation is the oldest one: He's a monster, created by James based on the picture he saw at the Historical Society, witch is based on the executioners like Jimmy Stone, witch is based on Valitel.