I'll try to state the thought more simply. "God" is a name we assign to the force behind the original, unexplained creation. Presently that would be the force behind the origin of this amazing universe, light, space. Maybe we push that envelope further in the future, but the boundary always exists. In our understanding there always is a 'first'. We have only the vaguest idea in a cosmic sense how that first came to b…
This is simply a God of the gaps argument [0]. Just because we don't (yet) know how the universe was created does not mean that we must attribute it to some deity. [0] https://en.wikipedia.org/wiki/God_of_the_gaps
"God, that is, Nature..."