Why the limitations to one God?

Because of divine simplicity, the absolute maximum of perfection logically excludes the possibility of more than one.

if there were two gods, they would have to differ from each other in some way. But a being that is pure act (without any potentiality) and absolutely simple (not composed of parts) cannot have any accidental differences. They could only differ in their very “whatness” (essence). However, if they differ in essence, then one has a perfection the other lacks. The one lacking that perfection would not be absolutely perfect, and therefore would not be God. Thus, you cannot have two beings each claiming to be the maximum of being.

Couldn't you suppose these gods had the same one-many property as the Trinity and say that it's whole essence is perfect?

If you need a god to explain where the universe came from, induction would like a word with you

My understanding of God is not “one more thing in the universe that explains an earlier thing.” It is closer to God as the ground of being itself: the reason anything exists at all, including matter, energy, spacetime, causality, and whatever laws describe them.

Then explain evil

Loaded (and begging) questions are a fundamental part of circular reasoning.

Occam's razor ("Entities should not be multiplied beyond necessity")?

I mean, God, isn't one enough? Honestly, it's too much for me!

Let's settle on having three then.

(If you had just one, it would look pretty silly calling himself father and praying to himself.)

By that argument zero is sufficient.

In nature everything has a opposite or opponent. That would make at least two.

Show me the opposite, or the opponent, of a black hole.

https://en.wikipedia.org/wiki/White_hole

I said show me, not point me at a hypothetical entity with no known pathway to reified existence.

> hypothetical entity with no known pathway to reified existence.

More realistic than god.

> More realistic than god.

No argument there, but “in nature everything has an opposite” is just as illogical; many things have no opposite, thus it’s not “at least two” it’s zero asshole gods in a nihilistic atheistic universe, one asshole god in a true monotheistic universe, one neutered god and one not-quite god representing the bit that’s been neutered off in a false monotheistic universe, one good god and one bad god in a morally balanced duotheistic universe (looks identical to the zero god(s) option), or a variable number of variably asshole gods in a polytheistic universe.