How to Know God Exists with an analogy: three skeptics are invited to witness a demonstration of electric power. They do not believe in electric power, because they cannot see it, unlike, apparently, the air they breathe, the gravity that keeps them and the air on Earth, or their own internal organs. These skeptics have the opportunity to test electricity by just flipping a switch and watching a light come on, but reject it because they find some apparent errors in a biographical sketch of Thomas Edison provided by the power company, and because electricity has been used to kill animals and people. They will not make the simple test to see if electricity is real.
Now, there are some minor disanalogies between Ray's imagined situation and skeptics' responses to Christianity.
For one thing, Ray wants us to test Christianity by actually believing and repenting. How does he know that we've done that? For that matter, how do we know that we've done that (I was under the impression -- which Ray rejects -- that at one time I had done that)? Apparently, the proof that you've really repented and believed is that you have the subjective experience of knowing God (and part of the proof that you really know God is that you keep saying you do; you never decide that you thought you knew God but were mistaken). There's very little room for controversy or differences of opinion on whether or not I've flipped an electrical switch (and if I refuse to do it, someone else can do it for me). But Ray can't repent for me, or tell if I've really repented or not.
Then of course there's the fact that the power company makes no claims that using electricity will make you a kinder, gentler person, or that "true electricity" can never be used for bad ends, or even that its brochures are completely inerrant. If electricity can be used to murder and to execute murderers, that has no bearing whatsoever on the reality of electricity or the truth of the power company's claims. But if Christianity does not change believers' lives -- or if it does, but there are so few true believers that they get lost in the masses of false converts -- that has rather more bearing on the claims Christianity makes for itself.
But this is Ray's fourth argument for the existence of (specifically the Christian) God: the personal experience of Christians. It is backed up by an implicit appeal to Pascal's wager. Some atheists are fond of attributing Christianity and Christian conversions simply to the fear of death and the desire to escape it. Ray's response to this allegation is to embrace it completely and enthusiastically: ten out of ten people die, he reminds us, and our fear of death is a God-given instinct driving us to embrace a chance at immortality when it's offered. Whether one can genuinely believe and repent out of fear of non-existence is an interesting question. Whether the experiences arising out of such belief are evidence of anything beyond a capacity for self-delusion is another. Ray has offered us, here, a reason (however strong or weak or contemptible you find it) to believe, but hardly a way to know that God exists.
This still doesn't quite get past Simpson's Rejoinder to Pascal's Wager: "But Marge, what if we've picked the wrong religion? Then every time we go to church, we're just making God madder and madder!" Ray still hasn't demonstrated that his parachutes work and rival company's don't, or that the Bible's threats of Hell are more credible than the Koran's.