1. Story
That's somewhat open-ended. I'm afraid there aren't many details available. I think this is intentional, as it lends an air of mystery to his reign. He's a mythical figure, and an even more powerful legend because he was real. He made the Dominion great. What else is there?
Source: Twitter2. Was Dominus story inspired by the bible
These themes are common to many cultural stories, but yeah - Dominus is definitely a Messianic character. But the basic setup with Dominus and Tresayne is actually one of the oldest pieces of lore in the game, surviving several complete IP overhauls, and actually precedes my start at Carbine in 2008. So I can't say for sure if that was the specific or primary inspiration.
Source: Reddit