I suppose a fundamentalist Christian could give a response along the lines of the part in the bible where Satan tells Jesus to throw himself off the cliff and his father will save him. Jesus replies something to the effect that, "thou shall not temp your god," or some such thing. I can't say that I know why the author said that but it would be my guess that it implies that god gave people a life and will and they should be used to the best of their ability to live life to the fullest that they can.
For a more practical and less religious thought on the subject...
I guess I don't really see it as a thought experiment. To say that it is a thought experiment is assuming that fundamentalist Christians don't value or have a sense of purpose in the life that they believe God gave them. Without that understanding it probably seems like a paradoxical thought experiment. Since an atheist believes that there is no spirit in the living and that there was nothing before or after their existence, why not just check in now? If this were economics, it could be explained that things have value not only at a particular place under current circumstance, but also a particular time in the future.
[youtube]http://www.youtube.com/watch?v=wWW1vpz1ybo[/youtube]
I'm not a fundamentalist Christian, and the only times I've ever been to church was when girlfriend asked me to attend with her. However, I have read the bible, as well as the Bhagavhad Gita, Tao Te Ching, The Tibetan Book of the Dead, among others, and found that I interpret it very differently than the ministers of organized religion do. Is your experiment is presented from a standpoint of a challenge or as a means of trying to learn something? What bothers me more than what somebody else believes, is when somebody else is bothered by what somebody else believes. That has always lead to oppression.