It seems paradoxical, but it is not.
Being an athiest is being a marginal or deviant or minority.
Minority groups may not be tolerant against each other and indeed it is so.
This is mostly because of being self-oriented or egocentricist. It is different from concentration camp psychology; me first, me second, me third, may be someone fourth, me fifth, me sixth, me seventh.
Minority groups mostly conflict with each other beacuse of they think that their problems are coming first, not other’s.
So being an atheist does not make someone a democrat, unfortunately.
I.e., atheists may be conservatives. Indeed many of them are so.
Most of people do not like real freedom. This is because of 5 millennium history-society-cage pschology. Social life is a safe cage for people. Even cage gate is open, they can not fly away to freedom.