Here's something I wrote years ago, but never published:
Baseball is life, or so the popular T-shirts read when I was in junior high. As such, whenever I struggled as a Little League pitcher to throw strikes, I would silently implore God to get me out of the inning. Likewise, I owned a maroon turtleneck that I usually wore underneath my jersey because I thought it brought me luck.
At the same time, I was an atheist. Contradiction? Yes.
It's contradictory to hold that a higher being somewhere out there does not exist, but that breaking a mirror will bring seven years of bad luck. Or that bad things happen on Friday the 13th. Or that voodoo dolls matter. Fundamentally, both superstition and theism rely on supernaturalism, or faith in a force beyond the laws of nature.
That's fine for most people, but it should be anathema for an atheist.