In a fascistic controlled society it is not sufficient just not to be a fascist, but rather it is compellingly necessary to be an anti-fascist. Just as in a racist society it is insufficient not to be a racist, but being an anti-racist is ethically required.
Similarly to the necessity for anti-fascism, anti-racism, anti-sexism, anti-speciesism etc. (which is in view of the parallels hard to deny) it is in our theistic dominated world absolutely insufficient just being atheistic.
Of course it's better being an atheist, instead of sharing the religious delusion. But atheism is not enough. Moreover it is necessary to act against theism. In contrast to the actual existing theism, antitheism is for ethically thinking and acting humans a must, an ethical imperative.
consequences of theism still are and always were devastating, regional as well as global. Whether religious wars, the crusades, indoctrination of children, genocide, tendency protection, omnipresent religious torture scenes, witch hunts, racism, slavery, or simply the Christmas television program. It is inevitable to fight for the separation of church and state, against the excrescences of religion, and the right not to be bothered by the scheming of the theists.
Of course antitheism does not mean a “persecution” of god believers (it is amazing that those people already associate this with simple atheism, the absence of believe in deities). Antitheism means rather to enlighten about reality, both scientifically and politically/historically. As much as it is necessary to tell children and teenagers (who believe in the baby-delivering stork) about the actual procedures in order to avoid or at least minimize unwanted pregnancies or that there is no Santa Claus, people must also be informed that it is not a God, who hurl lightnings or give them their daily bread wondrously. (Achim Stößer, tr. Jack Ryan)