Why Live?

This question from theists sincerely confuses me.  Apparently they are so invested in their religion, they just can't conceive of a life without it.  I personally like Carl Sagan's quote as a partial answer to that:

I would love to believe that when I die I will live again, that some thinking, feeling, remembering part of me will continue. But much as I want to believe that, and despite the ancient and worldwide cultural traditions that assert an afterlife, I know of nothing to suggest that it is more than wishful thinking. The world is so exquisite with so much love and moral depth, that there is no reason to deceive ourselves with pretty stories for which there's little good evidence. Far better it seems to me, in our vulnerability, is to look death in the eye and to be grateful every day for the brief but magnificent opportunity that life provides. 

Again, QualiaSoup (along with his brother TheraminTrees) has a beautiful video response: