[Edi]

No, the AI doesn't use your god. It randomizes a pretender for itself every time, and gets a lot of bonus points depending on difficulty level. High pathcost pretenders (like the Moloch) with two or three paths in the 7 - 9 range and a fourth one of around 5 or 6 isn't uncommon at Impossible level AI.

As for originals, there are no predesigned pretenders with the game. You need to create a god for any nation you wish to play first. That design stays there until you overwrite it with another one.

Edi