Stumbled across a documentary called God on the Brain from BBC that aired in April 2003. From that page:

"Rudi Affolter and Gwen Tighe have both experienced strong religious visions. He is an atheist; she a Christian. He thought he had died; she thought she had given birth to Jesus. Both have temporal lobe epilepsy.

Like other forms of epilepsy, the condition causes fitting but it is also associated with religious hallucinations. Research into why people like Rudi and Gwen saw what they did has opened up a whole field of brain science: neurotheology."

Interesting. I wonder what Richard Dawkins would have to say? Oh wait...

"Horizon introduced Dr Persinger to one of Britain's most renowned atheists, Prof Richard Dawkins. He agreed to try his techniques on Dawkins to see if he could give him a moment of religious feeling. During a session that lasted 40 minutes, Dawkins found that the magnetic fields around his temporal lobes affected his breathing and his limbs. He did not find god."

/me goes off to scour youtube and such places.