In the God Revisited column, Cecil says:
Most of the atheists I know have a very considered opinion, and while they tend to be argumentative, they also tend to have well constructed arguments.
In short, calling someone a knee-jerk atheist seems a bit like saying someone has a knee-jerk PhD; the lazy way to go is to believe what you’re told to believe, not spending time, energy and thought considering the idea for yourself.
I agree that entertaining the idea that there could be a God can be a enlightening process, but many people accept that notion simply because they’re told to. Knee-jerk Christians are more common the any brand of atheist.
If you tell someone you are an atheist you’re likely to get a lot of flak and argumentation. How much easier to simply go with the flow or simply not talk about your beliefs. Since a lot of atheists choose the latter, there isn’t a lot of discussion about it in mainstream society, so one has to seek out information and discussion on the subject.
For the most part, atheism is a thoughtful pursuit, not a lazy, brain-dead reaction to commonly held explanations for why life is the way it is.