The Cosmological Argument for the existence of God is an odd one to me in that it seems so simple. Some of the evidence behind it is not necessarily all that simple (specifically, the scientific evidence that shows the universe had a beginning and is not an eternally existing thing), but the argument itself and its premises couldn't be simpler. (I'll make the disclaimer if it's not obvious that none of this is my original thoughts... I'd have to give Frank Turek credit for boiling it down to such a communicable level.)
I've tried to imagine for a while what a Devout Atheist would have to say about it, and honestly, for the life of me, I'm actually not quite sure. So, I'd like to ask some of the DA's reading this to tell me what I'm missing.
* Everything that had a beginning had a cause.
* The universe had a beginning.
* Therefore the universe had a cause.
Obviously, everyone knows what a Christian is going to say this cause is.
Let me usurp what I think will probably be the first kind of response by posing it myself.
DA: Well, then who caused (or created) the first cause (or God)?
My answer of 'nobody' explained...
Since something exists (I assume we can agree on this), something must've always existed. For instance, you can't create yourself and you have to exist prior to creating anything. So, using particularly nebulous language, there must me something eternal out there.
That something eternal can be only one of two possible things:
Either the universe itself has always existed...
Or something outside the universe has always existed.
You'll notice this either/or brings us back to the second premise of the argument. I'm assuming we're in agreement about this premise that states the universe had a beginning since modern cosmology and physics has done a splendid job of showing us just that. So, since we know that the universe is not an eternally existing thing in and of itself, it would seem that it must be true that something outside the universe has always existed.
Given that the Book us Christians put so much stock in explicitly defines God as something that did not come to be, something unmade, something eternal that did not have a beginning (which means He didn't need a cause), it would seem like the Christian idea of God fits quite well with what the above logic (combined with the evidence provided by modern cosmology and physics regarding the non-eternalness of our universe) makes apparent.