I expect to have a conversation soon with my parents about cryonics. My parents are both professional scientists, but are vaguely religious. They certainly aren't fundamentalists; they are pro-choice, pro-gay rights, think "intelligent design" is nuts, etc. My father is less religious than my mother, the best description I can give is probably Deism. Doesn't believe in miracles, prayer, etc, but considers an afterlife likely. My mother is slightly more religious: in the past, she's prayed for help and things have worked out (positive bias). However, even she is far more skeptical than most theists. I remember one conversation as a kid in which she that she thought Jesus' resurrection was a metaphor. One one occasion, when I was in middle school, I asked her why she believed in God, and she replied that it was the only good explanation she could come up with for why there was good and evil in the world. She once quoted John Lennon, I think, talking about God as simply a personification of Good. She also believes in an afterlife.
Both of them I think would be very reluctant to engage in an open discussion about religion. In addition, both are intelligent enough, and have heard enough arguments, to make it enormously difficult to get them to change their minds, especially since the idea of an afterlife is a comforting thought for their own grandparents.
I would like to, if possible, avoid the discussion of religion, and instead simply persuade them to sign up for cryonics, without trying to force them to give up their belief in an afterlife. I've spent some time thinking about this, and have come up with some arguments. I do not want my parents to die. If there is any way I can be more persuasive, I have to find it, and I have to try it. So I am appealing to the collective brainstorming power of LW. If there is any argument you can think of that I can use, let me know.