Whatever begins to exist has a cause for its existence.
The universe began to exist (supposedly debatable).
Therefore, the universe has a cause for its existence.
For me, God is best expressed as a verb. God was. God is. God will.
Discussion
The problem (for me) with the Kalam Cosmological argument and other similarly ‘formal logic’ style arguments, is that you end up in metaphysics pretty quickly, arguing over definitions of words like ‘exist’ or ‘cause’.
I prefer the Moral argument, or the Finely Tuned Universe.
Christopher Hitchens apparently privately admitted that the one argument which most threatened to derail his atheism, was the Fine Tuning one.
The fine-tuning argument is derailed by the multiverse: https://link.springer.com/article/10.1007/s10701-023-00732-8
How so? That’s behind a paywall for me.