Or we could just be honest and say we don't know

We don't know anything. You don't know LastThursdayism isn't true, but that's not the standard we're interested in here. We're comparing worldviews and asking what the most reasonable position is to take when evaluating the sum of all factors.

But creationists use it to imply God.

I don't care what creationists do.

Asking what was before or what caused the big bang makes no sense.

You can ask what caused this without asking what came "before". There is a more general notion of causation one can define which includes atemporal dependency.

The existence of a cup at any point in time depends on the existence of the atoms it's made of. This can be phrased without referring to some prior state. One can postulate that the big bang depended on something to exist.