I'm reasonably familiar with relativity. Certainly nothing you have said about it so far is new to me. But you can't just invoke relativistic mechanics to demonstrate the logical consistency of the claim that a god can be omnipresent throughout the time line, in both directions, and at every location in space at each of those temporal points, and has been since the first moment of creation, while still maintaining that the future hasn't already happened. It's just not sufficient. What you need is something resembling the theory of special relativity with those additional metaphysical assertions factored in. If you have something like that, I'm listening. Explain away.