The point is that there is no reason to say that God made the universe, as the universe could have made itself. On that note, there is also no reason to say that God is self-created, as the universe could also be self-created.
If God is part of the universe, then his existence can be ascertained of by rational thought and science. There would be no further need for faith. This is not the argument that most theists play. They claim that God exists, yet we cannot make an argument in favor of His existence.
You are aware that every single thing in existence suffers from this same regress?
The causation chain either ends somewhere. A non-contingent being. Usually described as "self-created", or "eternal"/"atemporal". E.g. God, Energy etc.
Or, the causation chain is infinite. Essentially making the Universe itself the non-contingent being, since no individual being is treated as such.
A simple refutation:-
Numbers are infinite. They do not simultaneously contain all states. There are different states of infinity.