Attn: Theists - What would it take to prove you wrong?

[pineapplebunnybounce]

Premise 1 reads:

1. Everything that begins to exist has a cause.

Not.

1*Everything that begins to exist has a "known" cause.

Even on a charitable view of your objection that assumes we do not know what causes virtual particles to come into and go out of existence in the quantum vacuum, it simply does not follow that therefore said particles come into existence without a cause. At most, we can gather that said causation is "indeterminate". But this is not the same as "uncaused".

It simply is a non-sequitur informal fallacy to claim that our lack of knowledge regarding the cause of virtual particles necessarily means that they have no cause.

If scientists thought like this, and I am glad they do not, then it would completely undermine science! For whenever we discovered that we lacked an explanation for the way something came to be due to our limited knowledge, then we would have to say: "There is no cause! There is no explanation, it just exists, without a cause!" And throw our hands up in frustration and despair.

No no no....when we realize we lack knowledge regarding how something works or happens or came to be, this spurs us on to look harder, deeper into the matter. We don't take it as a sign to stop and say, there is no explanation!

Here's how it goes:
Premise 1: Everything that begins to exist has a cause.

This is a claim of knowledge. That everything has a cause. This you do not know. You cannot say that causation is indeterminate, because by doing so you are assuming there is a cause, when you have no reason to assume so. The correct conservative conclusion is we do not know if they are caused but right now there are no apparent causes.

Cthulhu Dreaming's conclusion was the correct one.