Back in my Saved! days, I was firmly anti-evangelization. As even cradle atheists can imagine, membership in an organized religion includes instruction in the art/skill of spreading "the good news"; from birth to death you are bombarded with the idea that a true follower of Christ is one who leads others to him both by example and by active evangelism.
[Note: I know very little about Judaism, Islam, or any other major/otherwise organized religion, and so I speak mainly of Christianity (Catholicism in particular), but there is no reason to suppose that my ideas (in general) do not carry over into those religions with which I am less familiar].
Catholics make rather light of the latter method in comparison to other branches of religion (i.e. Jehovah's Witnesses, Mormons, even Protestants), and so I suppose that's why I never really bought into the idea that Jesus wanted me to go about my life constantly attempting to "witness" to people. We focused instead on living in such a way that others would just need to know what we knew; ideally, the love of Jesus would emanate from my person in the form of neon lights shooting out of my ears and all who saw me would ask why was I so damned happy?
At a point, I also abandoned that theory. I came to the conclusion that Jesus was not always happy (Luke:42-49, to name one instance), therefore why must I always be happy in order to follow him? He was human, too, and had human emotions, and human emotions, even negative ones, can't be bad or God would never have lowered himself to take them on.
I have now asked myself the question of whether or not atheists, having rid themselves of religion, are obligated to attempt to do the same for others. I suppose that's a religious theory applied to a non-religion scenario: See, I have found the best way to live! All must do as I have done and ye shall thrive!
That's exactly what put me off Christian evangelism; it just seemed so ridiculous to presume that Everyone. Must. do what I did. I always felt that I should just do my thing and only talk about my religion if anyone specifically asked. God made free will, right?
However, if religion in any form is dangerous to society as a whole, as Sam Harris suggests in End of Faith (I have not yet finished even the first chapter of this book, so if I have misread the jacket blurb please correct me), do we indeed have an obligation? Perhaps, with so many completely avoidable evils running throughout the world, it's too urgent to just sit back and enjoy our freedom.
Do we owe it to ourselves, not to mention others, to eradicate religion?