There is an important if small distinction between an atheist who simply does not believe in a higher power and an atheist who believes that a higher power does not exist. The former is essentially neutral and does not believe in God, or whatever, and simply hasn't found evidence to support a belief in a higher power. The latter goes a step further and pretty much claims that there is no higher power or God. It is a small distinction but when you get down to it, it does make a big difference.
An Atheist that claims that a higher power can not exist or that God does not exist is making a claim similar to the claim that a higher power does exist or that God does exist. It is simply the opposite claim. One says he exists the other says he does not and ultimately neither can prove or disprove their standpoints. A claim that apples do not exist is as absolute as a claim that apples do exist.
To claim that I have found no evidence of a higher power is one thing... to claim that therefore the higher power does not exist is another matter all together. If you make the second claim... feel free to prove it. After all... such a claim is hardly scientific unless it is actually supported by evidence. And lack of evidence does not constitute evidence. We'll see whether you evidence does any better than the "evidence" that a higher power does exist.
Some claim that science conflicts with a belief in a higher power. But is that really true? Science is objective and tries to remain unbiased. Individual scientists might be swayed one way or another but ultimately science does quite well with regards to staying unbiased. Science is essentially neutral on the topic of religion and theism or atheism. Both sides, though atheism in particular, use science to support their viewpoints but ultimately science has not proved the existence or non-existence of a higher power. I have noticed that there are quite a few atheists here who fall under the category of those that make the claim that a higher power does not or can not exist. I challenge such atheists to bring forth their evidence. The other side of coin can play too... if you have evidence for a higher power bring it forth but beware you in particular will have a hard time on this forum.
For those of you who claim to be skeptics and simply don't believe anything without evidence this is you chance to reveal your true colors... are you truly just a skeptic? Are you truly objective? Do you really base your beliefs on evidence and experience? Or have you actually taken a standpoint and you look through a lens that aligns all evidence in support of your beliefs?
Let the Games Begin!