That's a good question.
Through the years, I’ve had a lot of discussions with atheists. I wonder sometimes, if they truly believe that when you die there is nothing and nothing mattered, then why do they often fight and argue so hard against theism and Intelligent Design? What are they so worried and upset about? Why spend so much of their time and effort (and even money) trying to persuade others and themselves that it’s not right? Why are they so angry about Someone they don’t even believe exists? If there is no meaning to life, why would you care if people are “deluded”? I think there is something else, deep down in their hearts.
For those asking why theists care... it's because we truly believe it and we are trying to save you. You may very well think we are crazy, but the point is that it's not coming from evil motives. And, maybe it's just me, but I'd much rather live next to someone who is taught to love his neighbor than a social Darwinist who may decide that he's more fit than I am.