To elaborate a bit, it works much the same way as speaking in tongues. Speaking in tongues is very easy, you can make any crowd of people do it as long as they're willing to follow instructions. Now, once you have the ability to speak in a "language" you believe to be outside of your control, all you need is initiative. The verse they use talks of speaking in the tongues of men and angels, which they interpret as meaning a divine language. If they're told that they're supposed to speak this language when they pray, and they have learned the speaking in tongues dynamic, naturally that's what will happen.
The only crazy part would be if you classify interpreting the Bible in that way as crazy, the actual speaking to God part is normal neurological response to the accompanying stimuli. So this person is not crazy, just under a crazy belief system.