Well to be frank, it never really does. In the king James version, the word “omnipotent” is used a few times, but the Greek word it was translated from was “almighty”. The problem isn’t in the word, but in the definition of the term. A conservative definition would be having unlimited power, or the the most that anyone can possess. Nothing in that implies that god is exempt from the laws of physics, nor is able to alter them at will. It only means that he has the Knowledge and the means to do whatever is possible within the system.
Genesis, King James version states:
A literal reading of the text implies that there was something before the earth. “The Deep” which was full of darkness. Space ought to fit that bill nicely. Then they mention that god was moving on the waters. I’m not certain at all what that means, but it would imply there is matter there at least. That means that god does not have the ability to create matter from nothing, it was already there to be manipulated. It implies that he does not have the ability to transmute matter to energy and vice versa either.
God then induces light to happen. he does then have the ability to either move stars around, or manipulate gravity enough to form stars and induce fusion. Good to know.
He separated the light from the darkness; setting planets into rotation is not a great task for a being who can manipulate gravity. God then goes on to play with the plate tectonics of the Earth and create land. Everything else follows, indicating a complete knowledge of matter manipulation.
So God by my understanding is a being who exists within the universe, but is in possession of the knowledge and means to completely manipulate matter. He then must be made of matter of some sort. Theoretically speaking, I agree with Der Trihs that a black hole ought to do the trick.