I'm pretty sure the devs said so during a community interview. Plus the very definition of a God is that they're creators. Daedra don't create things.

Oh and Boethiah denies that Daedra are Gods when u ask her/him about it in Skyrim.

The process Trinimac under went with Boethia was enough to "taint" him with that which makes the Daedra....Daedra, weather it be Purity, or sense what seperates the Et'ada are of Blood and intent, Trinimac whom once being selfless and cared for the weak, the pure and feeble and was finite has become a Dark Selfish being who dispises weakness and has become the antithesis of what he once was. I think thats enough to qualify him as a Daedra.

the others are just butthurt because he wasn't there in the beginning, and yeah I'd look down on my Spiritual bro too if he was the result of my sisters refuse.

Since when? God as in the capital G god doens't really apply to anything other then the God-Head (and even then) in the TES universe. Daedric Princes created their realms and everything within them, the only difference between a daedra and an aedra is that the aedra gaves themselves up in a community effort of sorts whereas the daedra did not and built their own worlds.