I am very skeptical of this psychic phenomenon and in most cases regard it as either a deliberate attempt to deceive or a manifestation of mental illness. I see no redeeming value in this practice. If it is of God, as some people claim, I find it hard to believe that non-sensical utterances are confused with divine instructions. So the claims that people make for their ability to speak in tongues become crucial to me.

Let me, however, file one caveat that makes some sense to me. A Pentecostal African-American preacher once said to me, "Glossolalia as an act of personal devotion is easy to understand."
"Tell me what you mean," I enquired.
"Well," he said, "When I make love to my wife I utter sounds that if played on a tape recorder, would be non-sensical to anyone else. But, inside our relationship of ecstasy, they are perfectly understandable. If my relationship with my wife can be marked with such intensity that it enables us to create an exclusive, but nonetheless to us a perfectly understandable language, as part of that relationship, is it not possible to do the same in our relationship with God?"
I could not rebut his argument.
I rest my case.

John S. Spong