The Unanswerable Question

When I was doing National Service in the army we used to get talks by vicars on religion. One of these was a drunken Welsh padre who, as early as 10 in the morning had had, you could tell, a few too many. So he stood there and swayed and gave us "the stuff" that was supposed to improve our moral well-being.
Most private soldiers like myself would take the opportunity to take a few much needed "40 winks", but there were others, corporals mostly, who listened attentively to the intoxicated Major.
At the end of the talk the major would make a big mistake; he would ask "Any Questions?"
Then it was that a certain corporal from HQ, a tall, scruffy-looking individual, would rise to his feet and say: "Yes sir, I have a question. It's this...."
At which point I would be in such a cringe-like state of embarrassment that I would try to pretend I was not hearing properly or pretend I was somewhere else, for the question the corporal always asked - to any visiting padre be it the drunken Welshman or the perfectly sober Scotsman - was unanswerable.
It was this: "As you know, sir, there are many religions in the world - Christian, Muslim, Hindu, Buddhist and so on - well, sir, which is the true one?"
I cannot remember what any of the answers were or if indeed there were answers at all because by this time I felt so sorry for the padre under interrogation that I was incapable of listening.
I wish I knew the answer to this question but I have the feeling that if I did I would then know the purpose of life in which case I might be disappointed.
When Bertrand Russell was asked what he would say if he found that after he had died he was faced with God. "I would say," said Russell, "why did you not reveal yourself to me before now?"