God is outside science. By nature it/she/he/them exists within a construct beyond measurement or human conception, and intended to be such. Depending on your cynicism towards religion, that's either for reasons of needing Belief-with-a-capital-B, or because scientific investigation could destroy the control a belief structure wields over its followers.
So God - or Odin, or Allah, or Shiva, etc - is not a theory in any case because it cannot be proven or disproven. I'd argue that faith is essentially worthless if it can be proven anyways, because the value of it is in the effort of belief.