If there is no after life

Part of the answer from person posting using profile "Should I" to the question that President Kalam asked on Yahoo Answers . [ Got this link via Desipundit ]

Education also provides the opportunity for us to instill the idea in children, early on, that killing human beings is cheating others of their opportunity to exist and fulfill their function in this world. Children need to be taught, with great repetition, that we have only one life... and thus, we must not take any persons life away from them, prematurely, because that is their ONLY life. Once again, this flies in the face of religion which often distorts the truth by telling children and adults that there is a "second" life, or an afterlife, "heaven", etc. There is no evidence of secondary lives or secondary existences... and this fact should be taught to children. If they realize they have one life, and the same applies for everyone, then they will be forced to deal with that fact when deciding whether, or not, to join a movement, such as that which we loosely refer to as terrorism

That life is precious is instinctively understood. We know that people who die , don't ever come back. But would this realization that there is no after life have impact on how precious we consider life to be? Would this also mean that people will be less inclined to sacrifice oneself to say rescue another human?