Why does God exist?

[Undeceived]

"why" is a cause question, so you're creating a paradox before we even begin. The only instance in which "why" would not be an investigation of cause is in a question like "why should God exist?" which focuses on God's effects instead.
Example (if you are skeptical):
Why are roses red? Because they were created/developed that way.
Why should roses be red? To please us/to attract bees.
As you will find, all physical objects work this way. God is not a physical object. He is out of our realm of experience. Any attempt to apply our universal laws to God will hit a dead end. God put his Word on earth to put Himself in our terms, to cross the boundary and communicate. But there's only so far He can go. Words like omnipotent and omniscient only just brush the ideas of transcendence and self-existence.

The "why" in my OP is not a cause question. I asked why does God exist as opposed to nothing. I did not ask "what caused God to exist."

Then give any example of a "why" question that does not necessitate a cause. Why do you do anything? There's a reason. Tell me one situation in which you can have a reason but no cause.

The idea that God is just a "brute fact" or "must have existed" I find intolerably strange. You're saying that it makes more sense for an incredibly complex, infinitely intelligent, and all powerful conscious personality to have existed first rather than just the universe by itself? The latter seems like a much more simpler answer.

According to our universal laws, everything needs a cause--including the universe. Therefore a force outside of our universal laws must be responsible. Why do you disagree with this?