We are looking for a complete, coherent, and simple understanding of reality. Given what we know about the universe, there seems to be no reason to invoke God as part of this description.

God is not described in equations.

There is no such thing as outside the universe, as far as we can tell.

Nothing in the fact that there was a first moment in time necessitates that an external something is required to bring the universe about at that moment.

We are looking for a complete, coherent, and simple understanding of reality. Given what we know about the universe, there seems to be no reason to invoke God as part of this description.

We are not significant on the cosmic scale.

All the stuff we've ever seen in the laboratory, all the kinds of particles and matter and energy, that only makes up 5 percent of our universe.