Many of the people making the claim for an after-death eternal life are often poor, uneducated and disenfranchised. Their lot in life is not a happy one.
Many of the poorest people in the world today have some kind of religious belief. It's quite understandable - when you have nothing and no hope of bettering yourself, what else is there to wish for apart from a quick and painless death and then an afterlife paradise free from hunger, pain and suffering? That is why religious belief thrives in poverty stricken countries. It's no accident that most of the world's religious people come from impoverished nations or nations that have, up until very recently, been impoverished.
The idea of an afterlife - a second crack of the whip so to speak - in a paradise that lasts for ever and ever is a seductive one to someone who has nothing and no hope. I don't think that any one of these impoverished people stop to think about what that actually means in principal. Why would they? Philosophy is a luxury - something to fill up your time when there's nothing else to do, such as feeding yourself and your kids.
That being said, I don't think that many educated, well-off religious people think about it either. It's an ephemeral concept that most people don't like to think about too much as it throws up too many unanswerable and uncomfortable questions.
Best not to think about it and just believe that God will sort it all out...