What always amuses me is that a great many theists (even those that seem rational) are taken with the notion that current models of physics and cosmology justify their beliefs. Mostly these are founded upon misinterpretations of these models, actually.
This is the "layman's" interpretation of the current state of cosmology: - There was an event (the big bang) that caused the universe.
The theists in question here then make the (completely unfounded) statement that god is the first cause (by no means demonstrated, and certainly doesn't favor a personal god over a nonpersonal god).
The actual situation is a terribly difficult one, and this layman's interpretation is a vast oversimplification.
1. Let's take the word "caused" to begin with. "Cause" implies that there is a sequential nature to events. That is, they are time-ordered. However, if there is no time, then there can be no causality (this is self-evident if you think about it). Asking what came "before" the big bang, or what "caused" the big bang, is like asking "what is north of the north pole"? (Thanks to Hawking for this wonderful analogy). As soon as you start going "more north" than the north pole, you start moving south again because you're constrained to the surface of the sphere. So the question is a nonsensical one from the get-go.
2. A proper theory of gravity (incorporating quantum mechanics) will necessarily be acausal below some time scale, unless general relativity is wrong altogether (which I don't see evidence of). Despite the protestations of certain people, this is the current consensus (and this is also a self-evident conclusion if one takes the merger of general relativity and quantum mechanics seriously).
3. The current models of "the big bang" actually only say that the observable universe, at some point around 13.7 billion years ago, was a very hot, dense entity which rapidly expanded and then cooled. It actually says absolutely nothing about what happened "before" this event (if such a concept is valid to begin with). There is absolutely nothing in the observable universe that currently states that the universe had a beginning. The current state of the art is that this question is, at present, unknown. An eternal universe that had a portion rapidly expand is completely adequate to explain everything we see in nature. There are a plethora of models that do not rely upon a "beginning" to the universe at all, ranging from cyclic universes in string theory involving brane collisions in higher dimensions, to a multiverse hypothesis. At present none are particularly preferred, but there are actually experiments that can be created to test these hypotheses (for instance, the LISA experiment will look for standing gravity waves to probe the structure of the early universe).
Because of 1 + 2 above, philosophizing about the nature of the origins of our universe is pretty difficult. Philosophy already assumes a causal relation of events. As I've argued, when dealing with the early universe, this may not be (and probably IS not) a good assumption.
Because of 3 above, in any case, even assuming a causal nature of events in *some* sense, the beginnings of the universe are still very much an open question with no resolution (CERTAINLY none that support the Christian ideas of a creator deity that takes a personal interest in day-to-day life and morality).
Subsequently, it always amuses me when theists oversimplify the situation and select the portions of it that support their presupposed "conclusion" (this should start ringing bells in any scientific mind).
I hope this sets the record straight and I've convinced the amateurs that they're really barking up the wrong tree. I have a feeling it won't, because human beings are necessarily terrible at intuitively grasping things outside of macroscopic physics, since they have no direct experience with the consequences of any other type of reality. Suffice to say that reality is a great deal more complicated than that, and one must abandon intuition to make any headway at all. But at least I gave it a shot.
by Rappoccio of AvC