Drew,
You claim that the probability of the universe existing on the assumption of a creator is greater than on the assumption of no creator. This is wrong. The a posteriori probability of the universe existing is 1. The a priori probability is unknown and unknowable, because the concept is undefinable. If the universe is a one-time-only coming-into-existence event, no probability can be ascribed to that. If the universe has always existed in some form or another, which is likely the case, then again it is meaningless to ascribe an a priori probability to this fact because there is no prior state of the universe. Either way your probability argument fails.
Your naturalism of the gaps argument fails. The reason we deploy the god of the gaps argument is because naturalism always supplies a necessary and sufficient explanation for what we see. When there is as gap in our knowledge, we are therefore inductively justified in believing that the gap will be filled not by god but by a natural explanation, because all such gaps have been so filled in the past. For the naturalism of the gaps argument to succeed, it would have to be the case that we had determined that everything we see had been created by a god, and therefore a naturalist explanation for a gap in our knowledge is not warranted. Needless to say this is not the case, and so there is no such thing as a naturalism of the gaps argument.
Your cosmological argument fails. If the universe needs a creator, then who created God? If God indeed needs a creator, then is it creators (turtles) all the way down? Summoning Occam’s Razor.
In Kalam variant of the CA, everything that begins to exist must have a cause. The universe began to exist, on this argument, so it must have a cause. The cause is held to be a transcendent creator who did not begin to exist because the creator is a necessary being.
The argument fails on two counts. Virtual particles come into existence without a cause, so the claim that everything begins to exist has a cause is false. Second, even if the claim were true, there is no evidence that the universe as a whole began to exist. The big bang is not evidence that the universe began to exist. It is evidence at best of a phase transition from a prior state, which will not be understood unless and until we reconcile general relativity with quantum mechanics. The conservations laws, which state that matter and energy can neither be created nor destroyed, powerfully point to a universe with an infinite past and future extension.
Moreover, as others have pointed out, even if the big bang were a temporal past boundary to the existence of the universe, it still follows that there was no time that the universe did not exist and there will be no time that it does not exist. This is because space and time only exist within the universe and there is no prior time to the big bang (if the bang really is a temporal boundary) in the same way that there is no direction north of the North Pole.
You stated that atheists claim to know that there is no creator of the universe. This is false. Atheism is a belief, or lack of belief, claim. Knowledge has nothing to do with it, only evidence and argument. Gnosis = knowledge; a/gnosis, or agnostic, means no knowledge claim. I am an agnostic atheist on that account.
Finally, even if it were true that everything inside the universe that began to exist has a cause, which is not true on the evidence of virtual particles, the argument is a standard composition fallacy. It does not follow that even if everything that begins to exist within the universe has a cause, then the universe itself must have a cause.
All your arguments fail. Do you have anything else?