There were two main objections, which my atheist opponents defended during the VT debate on the existence of God. One of the objections was from the problem of gratuitous evil, particularly natural evil, which I have already responded to here. The other objection raised during the debate was presented first after my opening statements. The argument was that because me and my debate partner were Christian theists the Christian God cannot exist because of the supposed atrocities in the Bible and other doctrines such as hell.
The argument began with the problem of predisposition. In other words, why you must approach your faith of choice with objectivity and skepticism and not confirmation bias. However, in response, in order to identify and affirm the discovery of a truth one must not exhaust all possibilities. Additionally, it works both ways. If the criterion is applied fairly how can one deny the proposition, in this case, God exists, without examining all possibilities? This criterion is untenable. Also, to suggest that one is a Christian because of environment or spatiotemporal location is to commit the genetic fallacy.
In this context, what I mean by contingent is that if X is contingent then X owes its existence to something else. For a thing that has the potentiality of movement cannot actualize its own potential; some other thing must cause it to move. The universe consists of a network of causes. A was caused by B, but only because B is caused by C, and so on. We know of nothing that spontaneously initiates its own causal activity. (Even supposed quantum indeterminacy requires a state of affairs, or preceding causal conditions, such as the governance of the laws of nature, for the event to occur). This is a hierarchical network of causation and not temporal. Note that nothing here turns on our having to know about everything.