Life was a lot simpler back when we didn't understand anything and it was easy to just posit God (or gods) as the explanation for everything. Why did the sun rise each morning? God did it. Why did it rain yesterday? God did it. Why didn't it rain today? God did it. How did we get here? God did it. Why is there so much pain and suffering in the world? God did, er, well let's just change the subject, shall we? We laugh at ancient cultures who invented gods to explain natural phenomena that we fully understand today. And yet, some still cling to the "god" explanation for the few things that we still don't have good explanations for (or things which they personally don't understand).
As our knowledge of the universe has expanded, however, we've pushed the necessity for God as an explanation into a smaller and smaller box, until he's limited to having started the whole thing in motion in the first place but hasn't really done much since then.
Science has done a wonderful job of explaining just about every facet of creation to the point that "God" is no longer a necessary explanation for anything. We're still a bit fuzzy on how it all got started in the first place (although I don't think modern scientists actually think it all suddenly appeared "OUT OF NOTHING"). At most, that leaves open the possibility that some sort of "god" started the whole process going and then left it to run unassisted. Since there's no actual evidence of such a god apart from our lack of understanding, however, there's really no good reason to assume that such a god actually exists. Any more than there was a good reason to assume the existence of Thor simply because we didn't understand how thunder and lightning happened.
Yes, scientific theories come and go (or get refined over time), and some things that we think we can fully explain today may turn out to have a different explanation later on. But (and this is probably the most important point of all) even if every single scientific theory ever advanced to explain the universe was completely and utterly wrong, there still wouldn't be a single bit of good evidence to believe in the God of the Bible (or any of the many, many other gods that have been written about over the past thousands of years). And there are plenty of Muslims who are just as convinced that Allah, as described in the Koran, is the one true God and not the God of the Bible and they make the same exact arguments as Christians do to justify their belief. They are just as sure, just as convinced, and just as wrong.
Some have argued that since “science” (or, more properly, the scientific method) does not currently provide an overarching and all-inclusive description of reality, we therefore need God to explain what science cannot. To this argument, I offer the following rebuttals:
- The proper question is not does science offer an overarching and all-inclusive description of reality, but whether it can offer such a description. Just because we can't explain everything at the moment doesn't mean we won't ever be able to.
- This is a false dichotomy. Even if science can't explain everything about everything, that doesn't mean that religion can (or that it can explain the "gaps" where science fails). Made up stories by ancient civilizations have no claim whatsoever to any sort of explanatory authority.