By definition atheism is closed minded.

Is it, really? I find more open mindedness in "there is no evidence for this, so I have no reason to believe it" than any theism. Someone telling you to be open minded usually means they want you to agree with them: Accepting a solution instead of considering others as well. It's happened to me, when people talked about ghosts, which have been disproven regardless. But then, it's just accepting one seemingly possible solution.

If all unlikely explanations seem possible, how is it open minded to select just one?