Um, two points:
As far as I'm concerned being atheist isn't "something in particular". It's a stance on a single issue. I'm an "atheist" as far as stamp collecting is concerned and, especially, football (soccer).
But no one (generally) tries to promote stamp collecting (I won't speak about soccer fans!) as a way that "others should subscribe to for the good of... whatever". I've never had stamp collectors knock on my door and tell me if I don't follow their teachings I'll spend eternity in hell. Etc etc.
As for "reactive or defensive" I've already given reasons (excuses?) for the reactive part, and yes some do get defensive. Again because we have been, at various points in our lives, subjected to varying degrees of "harassment".
I used to be quite squeamish about being preached to in one kind or other, I found it to be tantamount to bullying.
But after having read some literature on bullying, I have come to positively consider the idea that bullying can actually be good for one.
E.g.:
Why it's not always bad to be bullied: Learning to fight back helps children mature, says study
Read more: http://www.dailymail.co.uk/news/art...-Study-finds-fight-popular.html#ixzz1F0PXZK6k
Bullying can be good for children
http://www.timesonline.co.uk/tol/news/uk/education/article7133986.ece