Terorrism

Death is certainly a terrifying concept for most people. Eternal oblivion is simply not something we look forward to. It's no surprise, then, that most belief systems have capitalized on this, and attract people on promises of eternal life, and so on.
This is a swindle of the highest order, of course. No one is going to come back from the dead to claim a refund. Furthermore, we know from medecine that there is nothing that survives death (as oxymoronic as that is), no souls to fly around for eternity. The belief in such things must inevitably be rooted in superstition.
However, most people do believe in afterlives or a survival after death of some kind. And certainly, many of them do claim to be more moral or generally superior because of this belief. They feel they have more to live for, and that they are free from worries. It is interesting, by the way, to note that christians call themselves "dead to the world" - perhaps an interesting choice of words. Atheists, on the other hand, are free to become criminals and generally immoral people, since death is knocking at their door and their lives have no otherwordly significance.
However, what are the real consequences of such a belief ? They are quite the reverse. Reasonably, atheists are aware that this is the only life they get. Therefore one must act in order to maximize one's survival. This includes being benevolent towards other people - you can't go very far in life if you're totally against others. At least a certain degree of cooperation is necessary. The belief in an afterlife, however, removes this necessity. If death is indeed not death at all, but only a stage, then the consequences of our actions are relatively irrelevant. One may cheat and lie in the name of religion, even kill oneself and murder others, and one reaps the benefits of such actions without suffering any consequence. As such, the scarcity of life is the main motivator of ethical action.
We do observe that suicide cults inspired on religions have existed for millenias. However, it has been shown that suicide rates decrease with religiosity (P.F. Fagan, Heritage Foundation, 1996). It is not a causal link as such, but there is certainly indication to that effect - it would also be nice to have age-related information on that subject. At any rate, the makers of Christianity were not stupid, and made suicide a sin. Religion also brings a sense of well-being, which may reduce the desire for suicide, or reduce stress. This is not unique to religion, however.