Why do you not believe in God?

[ktulu]

Well, it is question begging because premise 1 breaks all things down into things that begin to exist, and things that do not begin to exist. In order for the argument to not be question begging, the subset of things that do not begin to exist needs more elements other then "THE CAUSE". Otherwise your argument becomes:

1. Everything that begins to exist, except for THE CAUSE has a cause.
2. The universe began to exist (due to THE CAUSE)
3. Therefore the universe has THE CAUSE.

I can kick KCA around more if you want to in a different thread, I don't want to douchjack this thread.

No, that's not true. Say that the set of things that "begin to exist" is B, and everything else is in B'. Let Q(x) be the proposition "x has a cause".

According to your argument, if B' = {THE CAUSE}, then (1) becomes:

1. For all x in B, except for THE CAUSE, Q(x)

But this is not question begging; there is no exception being made for THE CAUSE, since THE CAUSE is not in B.

And how do you know that THE CAUSE doesn't begin to exist?

lol,
very good self refutation on the last line.
If THE CAUSE began to exist it would be x.
The argument is question begging because you are not trying to prove that the universe has A CAUSE, but that the universe has THE CAUSE.
You cannot use the thing you attempting to prove in your premise. You arrive at a self contained circular mambo jumbo.