This is in response to a subthread a while ago (before I joined DU) where the poster challenged atheists to explain how the universe came about. I would like to respond, but first I would like to say that this is the first of five related posts. You see, IMO, religion is both an idea and a tool, and like all other ideas/tools it is a product of the human imagination. Given this, like all other ideas and tools, it is designed to fill a need; in the case of religion I think that there are five basic human needs that it was invented to fill. One of the most important of these needs is to explain existence.

Now, when people ask where the universe comes from, they are really involved in asking a more fundamental question, which is about the existence of ANYTHING. This question, in turn can be broken down into two distinct questions: WHY things exist and HOW things exist. The first question is not discussed much (nor I suspect thought about, with good reason IMO); the second is the most commonly brought up. Lets look at each of these aspects of the existence question.

WHY THINGS EXIST: I was a Philosophy major as an undergrad, and spent some time thinking about things like this as part of my courses. It seems to me that not only would it be more logical for NOTHING to exist (no objects, no energy, no time, no space), but it seems that that should be the case (the way things should be, or not be in this case). It would certainly be less messy than having all this random STUFF floating around in this weird THING (because space seems to be a thing) called SPACE, going through an even stranger and more incomprehensible thing called TIME. Obviously, it is wrong to think that non-existence is more logical, because non-existence is clearly not the case. Why is that?
After much thought, I can not think of WHY things exist rather than nothing existing, nor have I ever heard a coherent explanation from anyone else. In fact, this aspect of the existence question (WHY do things exist INSTEAD of NOTHING) is rarely addressed, which brings us to the next part of the question.

HOW THINGS EXIST: This part of the question is the one that everyone wants to cover ("How did the Universe come into being?"). Given the caveat that we are really talking about some general THING or THINGS existing rather than the specifics of the universe (which is a subset of the greater set THINGS), we can proceed. Again, after much thought in my classes, I came to the conclusion that there are two possibilities for HOW things came to exist, and I can not conceive of nor have I ever heard of any other possibilities. The possibilities seem to boil down to:

A. some thing(s) HAVE ALWAYS existed, and other things may have flowed from them latter.

B. some thing(s) SUDDENLY "popped into existence", after which all other things came.

I dislike both of these possibilities, for different reasons. Possibility "A" with its infinite chain of causality violates my sense of cause and effect. Possibility "B" offends me because it violates conservation laws. Neither satisfactorily explains HOW things came to be, yet those seem to be the only two possibilities (another reason for arguing that nothing SHOULD exist; it is less messy to explain non-existence than to explain existence).
Theist arguments that I have heard addressing the HOW issue tend to beg the basic question, or or be unnecessarily complicated (which I reject by Occams Razor), or both.

Discuss.