Interesting perspective, by an atheist, on why atheists oblige Christians on debating the existence of God.
"Even if atheists never wrote another book or blog post, young people will continue to fall away from Christianity. We can always help the process move faster, though, by constantly discussing/debating these issues in our communities, challenging the lies they tell, pointing out their hypocrisy and intolerance at every opportunity, and giving brand new atheists a community to join when they leave their Christian groups.
The Church is doing the bulk of our work for us. But there’s no reason we can’t help them out."