"First, when the universe began there was no God"

I don't see how this follows or doesn't follow from physics. Certainly, according to physics, God is not necessary. But to most believers God is not something that cares about physics, because God exists outside physics. Physics can only comment on what is governed by physics. Telling people they are ignorant does not refute this basic objection.

I'll put in another way. Perhaps we can say everything we want about the closed (let's just say 10-dimensional) manifold on which we live. We can pinpoint exactly where the negative signature of the metric degenerates, we can solve Cauchy problem for all time, or whatever. How does that tell us any information about a larger ambient manifold, or any disconnected components of the manifold? After all, Nash's Embedding Theorem holds for all signatures.