Spiritualists by definition turn themselves in Gods. To believe in an afterlife in any sense, you must therefore believe that you are immortal.
I would wager that the idea of an afterlife came from people who genuinely feared death and were in denial about it. Thus, the belief that they live on into another realm where they become immortal spirits or recycled into another animal or whatever is a comforting way for them to dodge the reality of a situation. Spiritualists (which have been debunked for about 300 years) saw the niche market and filled it. The fact tha there are literally books from the top guys in the business teaching you how to fake this should be a bit of an indicator towards its reliability.
I would wager that the idea of an afterlife came from people who genuinely feared death and were in denial about it. Thus, the belief that they live on into another realm where they become immortal spirits or recycled into another animal or whatever is a comforting way for them to dodge the reality of a situation. Spiritualists (which have been debunked for about 300 years) saw the niche market and filled it. The fact tha there are literally books from the top guys in the business teaching you how to fake this should be a bit of an indicator towards its reliability.