Of course it matters! Anyone it doesn't matter to doesn't value life, regardless of their religious beliefs. In fact, I'd suggest that it matters more to atheists since they are more concerned with that which is real and tangible. It would matter less to Christians because according the majority of them think that "God so loved the world that he gaveth his only begotten son; so that whoever believeth in Him shall have eternal life" - meaning you get to Heaven just for believing that Jesus was God incarnate.