[Note: This month, Patheos is organizing a “Why I Am A…” blog series, challenging contributors to explain the basis for their philosophy in 200 words or less. Here’s my contribution. —Adam]

I’m an atheist because personal experience isn’t sufficient.

People from every religion claim to have personal experiences that bolster their beliefs, whether it’s the warmth of God’s love or the cool knowledge of a moral lawgiver, the Buddhist satori or the Mormon burning in the bosom. Clearly, these mutually exclusive revelations can’t all be right.

To declare that a personal, inner experience gives certainty about the workings of the universe is to assign far too much value to one’s subjective sense of conviction. I’m not that arrogant. No matter how confident I am, I may still be mistaken, and the same is true of every human being. The brain, marvelous instrument though it is, isn’t infallible. It can misfire, seize or hallucinate, and it can do so in a way that’s utterly indistinguishable from reality to the person experiencing it.

That’s why the only reliable road to truth is empirical evidence, repeatedly tested and rigorously vetted, relying on no one’s testimony or mental state for its reality. And that’s just what all the religions of the world fail to offer for their outlandish, supernatural claims.

UPDATE: Here’s another post on the same theme, via Spanish Inquisitor.