Professor Richard Dawkins had a chapter in his recent book The God Delusion that was devoted to the probability of God. The idea is still very much ingrained in the minds of theists (committed or not) that the probability that a god exists is exactly proportionate to the probability that a god does not exist. Many people think it's 50/50. You can't prove nor disprove the existence of god, so that gives him a 50/50 shot at being real, right?
Know When To Walk Away...
Wrong. Those who think so don't truly understand the laws governing probability. Suppose you are in your car driving toward an intersection. The choice is: do you stop at the sign? Well, you either will or will not get hit by an oncoming car, so your chances are 50/50, right? Again, wrong. I hope this simple analogy illustrates the point that just by having two choices doesn't automatically place said choices on equal footing. This should be obvious to anyone -- but if you still don't think so, I hope I won't meet you out on the highway.
In his chapter on the God Hypothesis, Professor Dawkins looks at a "spectrum of probability", with seven benchmarks ranging from "I KNOW there is a god" to "I KNOW there is no god". Both such claims require evidence to be taken seriously. Dawkins then goes on throughout the book showing the so-called "evidence" for God's existence is nothing short of infinitesimal. In short, there is more evidence in favor of no god than in favor for it.
Because We're Here...
But Christians, Muslims, Hindus, Janists, Zoroastrians, or any other God-believing school of thought would say otherwise. It is in the area of scientific inquiry that the claims of evidence for the existence of deities must be tried and tested. So far, those tests have shown absolutly nothing supernatural or God-like. Perhaps one day we'll find a nugget of evidence that can't be explained any possible way other than appeals to God, but such a day would also morn the loss of science itself. For simply concluding "god did it" is not an answer. There will always be questions. How did "god" do it, exactly? With what? And what IS this god anyway? To throw your hands up and say "god" is to embrace ignorance and bemoan true understanding.