Absorbing a new study from the University of Tennessee, Andrew Brown delineates the different ways of being godless:

The largest group (37%) was what I would call “cultural non-believers”, and what they call “academic” or “intellectual atheists”: people who are well-educated, interested in religion, informed about it, but not themselves believers. I call them “cultural” because they are at home in a secular culture which takes as axiomatic that exclusive religious truth claims must be false. Essentially, they are how I imagined the majority readership of Comment is Free’s belief section. They are more than twice as common as the “anti-theists” whose characteristics hardly need spelling out here:

If any subset of our non-belief sample fit the “angry, argumentative, dogmatic” stereotype, it is the anti-theists. This group scored the highest amongst our other typologies on empirical psychometric measures of anger, autonomy, agreeableness, narcissism, and dogmatism while scoring lowest on measures of positive relations with others … the assertive anti-theist both proactively and aggressively asserts their views towards others when appropriate, seeking to educate the theists in the passé nature of belief and theology.

Nonetheless, these people made up only 14% of their sample, and all other research that I know of would place their proportion much lower.