An interesting study of people with a certain form of epilepsy has shown that they are prone to religious visions, and a connection made with one of the founders of a religious sect (the Seventh Day Adventists) seems to confirm this. The study is in more detail here, and seems to point to a 'source' in the brain for religious type thoughts.

 

http://news.bbc.co.uk/1/hi/sci/tech/2865009.stm

There apparently was a Times article about ergot and hallucinations - linking it to "religious" experiences - same thing or not?

Sort of. Temporal lobe epilepsy (TLE) is a medical condition. It's a very weird form of epilepsy. Ergot is a fungus which infests wheat and is toxic and extremely hallucinogenic. The similarity is in that ergot produces nurological effects in some (but not all) of the same brain areas that are affected by TLE. The generator loci for TLE, as the name suggests, lie in the temproal lobe, often the medial region and around the hippocampal formation. This may account for some of the strange effects of TLE compared to 'normal' epilepsy.

 

Interestingly, there is a correlaton between outbreaks of ergot infestation and witch hunts/witch burning. It has been suggested that people eating bread contaminated with ergot had hallucinations and displayed strange behaviours resulting in their being accused of witchcraft and/or satanic posession and leading to a witchhunt. Often entire villages would suffer the effects of ergot poisoning, which is not surprising as there would usually only be one baker, baking bread from the crop grown by the village.