You cannot even say “God exists outside of the universe”.
That makes no sense. The word “universe” is not well defined.
However, if we define the word “universe” to mean a category that includes everything we think existed in the past, exists in the present and will exist in the future, basically, if by “universe” we mean everything existent, then to say that God exists outside of the universe means to say that God is not among those things we consider to be existent which is a very convoluted way of saying that GOD DOES NOT EXIST.
The word “universe” is simply an all-encompassing category that includes everything we consider to be existent.
Whatever is outside of it is that which we consider to be non-existent.
Also, we cannot say “the universe began”.
That’s horse-shit.
These words only make sense in the context of a sequence which is an ordered set i.e. a set where each element has a position, an index, a number indicating its place in the set.
With sequences we have first element, second element, third element and so on until the last element.
The universe can be thought of as a set of everything we consider to be existent.
But not an ordered set. And even if it was made into an ordered set, say by ordering everything we consider to be existent based on the time it is supposed to exist in, its first element (beginning) and its last element (end) would only refer to the limits of our knowledge.
Our models can project as far as we want them to project into the past and into the future.
There are no limits.
What we can say is “the Earth began”.
Earth refers to an observable . . . something that has limits, and therefore, a beginning and an end.
You can ask “how did the first life on Earth come into existence?”
That’s a meaningful question.
You can’t ask “how did the first life in the universe come into existence?”
That’s meaningless.
If you say that life on Earth came into existence due to some intelligent force outside of the Earth, then you’re speaking of aliens.
Is God an alien?
Maybe he’s not an alien, maybe he’s some kind of “force”.
That makes far more sense than what Christians are trying to sell us.