Atheists are also morally obligated to tell the truth as we see it. We should preach and proselytize too. We need to help believers. Someone who believes in god is wasting big parts of his or her life, holding back science and love, and giving "moral" support to dangerous extremists. If you believe something, you must share it; it's one of the ways we all learn about truth.
p. 62 - God, No!: Signs You May Already Be an Atheist and Other Magical Tales (2011)