They do. Science seeks to answer everything about the universe. Science is the study of the natural world, and that necessarily dictates that we try and figure out why and how everything happened. Religion seeks to answer the same thing. The simple fact of the matter, Pumpkin, is that the two frequently DO clash because they seek to answer the exact same questions, but Science doesn't necessarily grant the existence of a God until it can be proven....which is surely the reasonable thing to do. If you accepted every claim that was made without evidence that it was true, you'd wind up believing absolutely everything, regardless of how absurd it was. The simple flaw in your first paragraph is assuming that the two inhabit separate spheres, when in fact their domains overlap. Science seeks to explain the natural world with natural explanations through rigorous testing and investigation (NOT just observation), and Religion seeks to explain it by appealing to an unfalsifiable God. If a claim is unfalsifiable, it is also unverifiable, and any claim that can be presented without evidence can be discarded without evidence. A good overview of that "separate spheres" argument was given (and rebutted) in Richard Dawkins excellent "The God Delusion," and no, I'm not about to quote the whole chapter.
As for your second paragraph...you're wrong. I'm sorry, but you are. You are right in that there are atheists who claim that no Gods exist, and if one should make that claim, they have to provide evidence because they're making a positive claim, but that is not necessarily atheism. Atheism is simply the lack of a belief in God. Saying you don't believe a claim until you've seen sufficient evidence is not the same as saying that you think that claim is false. It's like a court case; the verdicts are Guilty and Not Guilty, because the question is not whether the defendant committed the crime, but whether there is sufficient evidence
to convict. In the court of existing, I am finding the God Claims that I have been presented thus far Not Guilty of existing. I am NOT saying he is innocent of existing, just that the evidence presented to me is not enough to convict him. Now, there are degrees of belief/disbelief. You can be an Agnostic Atheist (like myself) who says "I don't believe in God, but I don't claim knowledge either way." I personally think that this is the most justifiable position; I don't believe the claims that have been presented based on the insufficiency of their evidence, but I do NOT make the positive claim that no Gods exist. Then there are Gnostic Atheists, who DO make the claim that no Gods exist. Similarly, you can have Agnostic Theists (who believe, but don't claim to know) and Gnostic Theists (who believe, and claim to know). However, having no belief is NOT a belief system. Atheism is the LACK of a belief, therefore, the lack of a belief SYSTEM. The difference is this:
A belief, as defined by every dictionary I can get my hands on, is a conclusion based on personal feelings and emotions rather than scientific evidence and critical thought. Most atheists base their lack of a belief in God or Gods on scientific evidence (or lack thereof) and critical analysis. Therefore, atheism is not a belief but a conclusion. Atheism is NOT a belief or a belief system. It is DEFINED as the LACK of a belief. And even IF one had the belief that a God did not exist, that would STILL not qualify as a belief system, because ONE belief cannot a system make.http://atheism.about.com/b/2007/06/11/atheism-is-not-a-belief-system-does-this-really-need-repeating.htmhttp://atheistfoundation.org.au/article/atheism-belief/
And even if it WAS a belief, so what? Not all claims were created equal, and in my eyes, it would still be more justifiable than the belief in a God, simply because there is no good evidence that we have access to to say that a God exists. Therefore, which is more reasonable: To believe on no evidence, or to reject the claim based on the fact that no evidence has been offered and verified to be legitimate?
Extraordinary claims (Eg, the existence of an omnipotent, omniscient supernatural being) require extraordinary evidence.
No evidence has been offered...so atheists are justified in rejecting the claim.