I'm still dipping into Christopher Hitchens' "Letters to a Young Contrarian" from time to time (it's kind of like a box full of really rich brownies...you don't want to eat them all at once).

Anyway, I liked this passage about Marx and religion, and about arguing with people who believe in god:

Time spent in arguing with the faithful is, oddly enough, almost never wasted. The argument is the origin of all arguments; one must always be striving to deepen and refine it; Marx was right when he stated in 1844 that "the criticism of religion is the premise of all criticism."