Perhaps the key challenge to veracity of religious experience is the claim that that there are alternative explanations; that these are not supernatural experiences of God, but are natural explanations, the result of brain activity, such as temporal lobe epilepsy.
This link between brain activity and religious experience have often been supported with reference to hallucinogenic drugs.
William James himself conducted experiments on himself using nitrous oxide.
He wrote that this:
‘stimulated the mystical consciousness in an extraordinary degree. Depth beyond depth of truth seems revealed to the inhaler. This truth fades out, however, or escapes, at the moment of coming to . . . .nevertheless, the sense of profound meaning having been there persists.’
Though the experience was the result of inhaling nitrous oxide, the experience sounds mystical. The ‘fading out of truth’ could be linked with ineffability, while the ‘profound sense of meaning’ could be the noetic quality. It is not just a strange, unusual experience, it is an experience that sounds like the kinds of experiences mystics have.
Another, more rigour experiment was conducted by Walter Pahnke at Harvard University. Known as the Good Friday experiment (or the Marsh Chapel experiment), he set up a test where 10 theology students were given psilocybin, a naturally occurring psychedelic compound found in over 200 species of mushrooms, while 10 other students were given a placebo. No-one knew who had been given which pill, not even those taking them. All the students then sat in Marsh Chapel and listened to a meditative Good Friday service. Nine out of the ten students who had been given psilocybin had something like a mystical religious experience. (Watch this for more details)
And the author, Aldous Huxley is anther for whom the link between drugs and unusual perception is strong. In his book, ‘The Doors of Perception’, he recounts his experiences taking the hallucinogenic drug, mescaline. His experiences again tell us of a deeper knowledge and awareness of the world and its true nature, as well as a loss of self and an emergence into a new reality. (Watch this for more details)
What these experience seem to show is that there is a link between what is happening in the brain and put experiences. When we affect the brain through the use of drugs such as psilocybin or mescaline, we can profoundly affect our perception.
This is not to say that in opposing the argument from religious experience we can simply say that Moses, Saul, St. Teresa and all the others were taking drugs. We have no such evidence to support that claim.
But what we could argue, similar to the arguments we saw about temporal lobe epilepsy, is that so called religious experiences have a natural explanation, related to variations in brain activity, and therefore, there is no need for a supernatural explanation.
Let’s return to our key question, Are religious experiences really of God?
Here the argument would be that they are not experiences of a supernatural God, they are experiences resulting from what is happening in our brains, in other words, these experiences have natural explanations.
If you’d like to learn a little more about the Marsh Chapel Experiment and Huxley’s taking of mescaline, then watch these brief YouTube videos.