They're either atheists, and believe that once dead, "it's over;" or, they recognize that atheism is really just satanism, and thus once dead, they'll be in for "eternal" torment (time does come to an end, so it won't really be eternal, but then I suppose it could be in a different dimension, etc). Either way -- because of their beliefs, they will give up everything, including other people, in order to "live another day" and perhaps, "another minute."