My friend Bishop Martin has posted an excellent piece on Contemplative Intercession which coincided with the first of John Humphries' programmes about religion, in which he interviewed +Rowan Williams. There arose the question - I suppose inevitably - about what someone who prays thinks he/she is doing to influence the course of events. +Rowan voiced the idea of prayer somehow creating a "thin-ness" so that the power of love could break through into a situation. +Martin writes about visualising someone for whom one prays - but I suppose to someone who never prays all answers such as these will appear nonsensical in the literal sense of having no meaning.
One of the best hours I ever spent in my teaching career was taken up by a discussion with a class of boys about what prayer actually is to those who do it. I resorted to the analogy of phoning home when you're away from your parents - they could accept that, but it's a difficult concept to introduce to a "cold" audience. In fact, I don't know how evangelism happens - not now, anyway, and maybe not ever.
Maybe it's a case of "come and see"?