why should a larger brain lead us to be capable of dreaming up things to believe in?
granted, religion does focus on death, and after death, and what it says is fairly unbelievable or too weird, because its the great unknown.
but why believe something just for comfort sake? i believe, not just because of its answer to that question (of what happens after death), but of what other questions its able to answer - why am i here, where did everything come from, why is there suffering, etc.
people who truly believe here, believe because these questions are answered concisely, make sense, and ties in together. answered separately, they sound foolish.
i don't believe that its important to make an impression on others, because those people will also die, and their memories of you with it.
coming from your perspective, i can understand that that's probably the only important thing that life can bring. i don't see how it makes the christian individual look selfish (unless your saying that the christian is only concerned with saving themselves, which isn't true - otherwise christianity wouldn't be expansionist)