Atheism is a lack of active faith, not the affirmative belief that god does not exist. An atheist could believe in life after death if you could show proof.
There are conservative and libertarian atheists as well as atheist gun owners. Equating atheism with liberalism is lazy and dishonest. Frankly, I find some of the most objectionable liberals to be ones who use their faith as a tool to evade scrutiny.
Finally, the atheist belief that "your child is at peace" is more comforting than the Christian belief that "you raised your child in the wrong faith so he will burn in hell".