Different atheists have different attitudes towards their atheism and the theism of others. One difference which gets a lot of attention and debate is whether atheists should adopt a "live and let live attitude" towards religion and theism or whether atheists should be more active critics of religion and theism. This distinction between passive and aggressive atheism is not new; it is in fact one which has divided atheists and caused arguments among atheists for a long, long time.
We can, for example, see atheists arguing about this in the 19th century. As is the case today, some atheists argued that it would be better to adopt a more conciliatory stance towards theism and religion — an atheism which may be critical, but doesn't go out of its way to criticize. Other atheists argued that the negative influences of religion and theism on society required a much more engaged, active criticism that deliberately seeks out the problems of religion in order to help construct a better future.
Political vs. Personal
The critical thing to remember about these disagreements is that they aren't simply about which tactic a particular atheist is personally more comfortable with or personally finds most productive. Instead, it's about which tactic atheists generally should adopt — it's about which tactic will, in the long run, be best for the atheist community and atheism itself. It's thus a question about political tactics more than personal approaches.
Defenders of the more passive approach for example argue that aggressive atheism makes more enemies than friends, causing religious theists to become defensive and less receptive to eventually adopting a secular, nontheistic worldview themselves. Defenders of a more aggressive approach argue that a conciliatory attitude only serves to perpetuate religious privilege in society and believe that none of the problems caused by religion will be solved unless people stand up and act more decisively.
Passive vs. Aggressive Freethought
In The Gathering of Infidels: A Hundred Years of the Rationalist Press Association, Bill Cooke writes:
The disagreement between Bradlaugh and Watts over their attitudes toward “The Fruits of Philosophy” goes to the heart of the division in the freethought movement around the world, then and now. People like Bradlaugh see their role relative to religion essentially as a combat role. Angered by the many errors in religious truth claims and motivated by injustices experienced at the hand of religious intolerance, they see their task as the elimination of error.
But other people within the freethought movement have a different focus. They are more likely to appreciate the inclusive, nurturing elements in religion, and seek to recreate some of that spirit in the freethought movement, minus, of course, the dogmatism and error. Colin Campbell has posited these two types as abolitionists and substitutionists. Bradlaugh and his followers had more of the features of the abolitionist strand in freethought. Charles Watts and his friends had more features of the substitutionist strand of the movement.
Both are legitimate and honourable facets of international freethought, but relations between exponents of each of these strands have often been tense, as this history will recall.
Principles vs. Pragmatism
These two approaches are motivated by two different values: principle vs. pragmatism. Adherence to principle would suggest that one be equally critical of both liberal and fundamentalist theists if you think that both positions are wrong. Pragmatism suggests that since it will never happen that everyone agrees with you on everything, then you will have to work with people you disagree with on some things in order to achieve goals on which you do all agree. This means you should avoid upsetting potential allies and refrain from critiquing them even in other contexts.
Thus we are presented with a fundamental problem: do atheists really need to just keep quiet about what they really believe in order to keep religious believers happy and avoid upsetting them? Well, put that way it almost sounds absurd — political pragmatism may exclude certain ways of expressing one's criticism of religion, but if you have to effectively stay in the closet just to get religious theists to work with you on things they already believe are right, doesn't that suggest far deeper problems with their own position?
It's Not Black & White
It’s possible to adopt both perspectives, depending on the context. Let’s face it, there are forms of religion which may be wrong and irrational, but also aren’t immediately dangerous in any political or social sense. Thus it can make a lot of sense to adopt a more aggressive approach when faced with more theocratic forms of religion but more passive when faced with forms of religion that may be rife with error but make no obviously harmful political demands.
It's also possible to adopt both approaches depending on their immediate social context. You may have a very aggressive and critical approach to religion when online when debating religion with other atheists or even theists, but then a more passive, "live and let live" approach when among family. Lots of people do this with politics and other issues, so why not religion?
Thus the problem or disagreement doesn't need to be as difficult as it is often depicted. If some atheists want to be more passive and conciliatory, whether in some contexts or generally, they should do so. If other atheists want to be more aggressive and critical, whether in some contexts or generally, they should do so. What atheists shouldn't be doing is insisting that all other atheists conform to a limited approach. It's wrong for aggressive atheists to insist that all atheists be equally aggressive all the time and it's wrong for more conciliatory atheists insist that all atheists be equally conciliatory all the time.