This question appears many times, and it is really getting quit boring.
But ONE MORE TIME:
In order for God to claim to be God, He must qualify as God; and to qualify to be God, He must have created this MEST universe. (MEST = Matter, Energy, Space and Time).
If God created this MEST universe, then logically He can not be part of, or consist of, that which He created.
God is neither matter nor energy. Jesus said God is Spirit.
God can not be limited to exist within space and time any more than an artist can be limited to exist within the canvas he uses to paint on.
God therefore, logically, must transcend space and time. That is to say, He is infinite in scope, and eternal in duration.
You can not logically apply the laws of this MEST universe (the laws of science) to that which is not MEST. It is neither logical NOR scientific!
Furthermore, the question "who created God" poses a logical contradiction, because if you ask who created God, then you must also ask who created God's creator, and who created that one's creator, ad infinitum, ad nauseum, creating an infinite regression of ever greater Gods.
If you go back to the very FIRST God of this infinite regression, THAT is GOD. The others are NOT God, because they were created.
This universe, however, being MEST, is obligated to obey the MEST laws of science, such as the laws of thermodynamics, the law of entropy, etc, thus the universe either had a beginning, or it is dead.
If it never had a beginning, that would make it eternal, and the 2nd law of thermodynamics demands that the universe would die off in a finite number of years. If you say "But the universe isn't old enough yet", you have just admitted that the universe is NOT eternal (infinite in age), but had a beginning. (You can't have it both ways - either it is NOT old enough to be dead yet and it DID have a beginning; or it is infinite in age (i.e. eternal), and it would have died out a long time ago.)
The universe, both logically and scientifically, had to have a definite beginning at some point in time a finite amount of time ago, and that includes any kind of "egg" from which the universe may have exploded. To talk about the "big bang" just begs the point, because we have the same identical issue with this singularity. If it was eternal, then it would have exploded an infinite amount of time ago, and the universe would have died out by now. If (and since) the universe is still here, the alleged "big bang" had to have occurred a finite amount of time ago, and the "egg" (singularity) that held the entire contents of this universe, only exploded a finite amount of time ago, thus this singularity has NOT been here an infinite amount of time ago (ie. not eternal), so this singularity had to have had a beginning because it, too, is MEST, and thus subject to the laws of MEST!
The ONLY thing that is NOT subject to the laws of MEST (ie. a beginning) is that which is NOT MEST (ie. God).
Now please, quit asking this same question over and over again, and for once try to think logically and rationally like you atheist mockers keep CLAIMING to do!