I thought I'd responded to this post before, but I've looked through and it would seem not. Your OP interested me. It made me think about both the promises and the threats of Christianity and Islam (and quite a lot of others too). They share one fundamental idea: that once brought about, consciousness will NEVER end. Whether after death you are being subjected to the most horrific torment - eternally - or having a good time - forever - at no time does consciousness finish for good.
I'd imagine that the difficulty in imagining an end to consciousness might help to explain why many religions do not find it possible to say consciousness ever ends.
I suppose this begs the question: are there religions that can imagine an end to consciousness (does nirvana count?)? Jar mentioned Judaism, but sounded a bit hazy. I think I'd be quite surprised if Jews unambiguously propose an ending of all thought and feeling. I've been wrong a million times before though.
So does that make most religions merely pills that people take for the ultimate headache - imagining what it is like not to imagine?
I dunno.