Atheism, Evidence and the God-of-the-Gaps

[Randy Carson]

If atheists say that atheism does not claim "There is no God," only that some people lack a belief in God, then atheism can't be true at all. A belief can only be true (in a non-trivial sense) when it makes a claim about the world and not just about someone's state of mind.

I think there's some confusion here, maybe from atheists you have spoke to or maybe just confusion in your own mind.
I'd never say Christianity is false and atheism is true.  I WOULD say the statements in the quran aren't miraculous and don't prove a god, and that the statements in the bible are ancient myths which most likely aren't true.  I might also say it's true that I lack a belief in god.
So in a way I agree with, the statement that atheism is true doesn't really make sense.  But most atheists don't say atheism is true [emphasis added], it's like saying communism is true, capitalism is true, table is true, lamp is true.  What most atheists do say is that the statements in the bible and quran and other religious books are false or just unproven to be true.

In their exuberance, I think some (even many) go further than that highlighted sentence.