But how do you know that God doesn't run His other universes in different ways? Maybe He's a loving, father-like God in our universe, a wrathful, vengeful God in another, and a neglectful, underachiever God in yet another. In other words, how can you presume to place limitations on God?
It isn't so much a limitation as an acceptance of the Biblical statement that God is One (in three "persons"). I don't imagine a God that deins to exist in an infinite number of states of Being across an infinite number of "universes," or observing from outside of that infinite number of universes. There's also the paradoxical idea that there would exist an infinite number of universes in which there IS no God, and an infinite number in which God is One, an infinite number in which there are an infinite number of Gods, an infinite number in which a particular rock or bird feather is God, and so on.
That's where the whole "infinite number of parallel universes" idea falls apart, in my mind. People tend to imagine this in macro-scale. There's a universe in which Hitler existed, and one in which he didn't, for example. The actual theory, compared to that level of simplicity, is insane. Such concepts as, for every drop of rain that falls on every square millimeter of earth, and on every earthlike planet in the universe, there are an infinite number in which that drop of rain landed a nanometer to the left or to the right of where it fell in this universe.
Really, even that is thinking in macro-scale - the reality would be that for every mere probability in, say, the track of every electron around every atom in the universe, there would be an infinite number of parallel universes in which that probability is different - and an infinite number resulting from each of those differences.
There are those who find this theory tenable. I personally don't. The only tangible evidence I've ever seen is the brief existence of antihydrogen - and I think even that is subject to different interpretations. Maybe it's the forcible extraction of the tiniest piece of "matter" one can pull from an adjacent dimension, rather than from the "antiUniverse."