Ok, been trying to remember/find this book for forever. Google, Amazon, Goodreads, none helped. Here's the synopsis:

God, Lucifer, angels, demons are all entities on a higher plane of existence who come from another dimension. They gain power and survive by having people pray to them (similar to the Ori from Stargate if you've seen that). They encounter earth and humans. God & angels decide to create Christianity to suck power/life force from humans. Lucifer & demons are against this, and fight God/angels to protect humanity. God wins, lucifer retreats and works more subtly to protect humanity against God's evil plans.

Anyone have any ideas? Really hoping for some help here.