The disinclination to believe that there is a supreme being can take various forms. The two that I will consider here are atheism and antitheism. I understand atheism to be simply the absence of the belief that a god or gods exists, or that there is a lack of lack of evidence for such an entity. On the other hand, I understand antitheism to be a doctrine which not only rejects a supreme being's existence but also actively opposes theistic religions.
This is not to say that atheism stakes its position in the spectrum of irreligion and passively lets it go at that. In fact, atheists who simply demand the right not to be persecuted for their non-belief and to be granted socio-political equality with theists are considered by some as "militant". But obviously, such freedom is of vital importance, especially in societies where the god-believers and their culture predominate, as in the U.S.
Antitheism, however, takes an antagonistic stance in dealing with religious beliefs. Its adherents who hold political power may even go so far as to try to abolish them altogether. An example is the Communist regime in China in its attacks on that country's religious communities, especially the imprisonment of the latter’s' members in "reeducation camps" in attempts to rid them of their theistic mindsets. Antitheism was likewise a pillar of the culture of the former Soviet Union. Under both the old USSR and modern China, the purported purpose of eradicating religion has supposedly been to replace the old superstitious ways that impede mankind's progress.
Towards this end, communist ideology (in which antitheism plays a vital role) claims to be a revolutionary movement, one which promises to create an advanced type of humankind who in turn would build a glorious new world. But the more likely reason is that religion is seen as a source of competition for the hearts and minds of the people. (This struggle is discussed in depth in “The Battle for China’s Spirit” by Sarah Cook). So In short, suppression of religion in China is simply a means of heading off a power struggle.
Personally, as an atheist, I’m put off by antitheism. I support people's entitlement to personal beliefs to the extent that those who hold them do not try to impose their creeds on others. Unfortunately, however, that ideal is not the kind of world we live in. Consider the existence of religious fundamentalism as enforced in such countries as Iran on hand and extremist antitheism as practiced in places like China on the other. That said, I must acknowledge that I don’t consider the boundaries between atheism and antitheism as absolute. There is no bright orange line separating them. For example, inasmuch as I don't believe in the existence of God, I think that the field of theology, which dictionaries define as “the study of the nature of God and religious beliefs”, is a waste of time, resources, and intellectual effort and therefore should not be offered as a separate course of study in secular universities over what is basically a myth. Instead, it should be included under mythology along with the study of other god legends of the world. So, with this point of view, does this mean that I have morphed into an antitheist? I’d like to think not. For one thing, I'm not proposing to scrap theology entirely, just to downgrade its undeserved status as an academic discipline and to place it under a more appropriate field of inquiry.
Finally, but significantly, there is the matter of the consequences of the inability to distinguish atheism from antitheism as it applies to god-believers who, because of this misunderstanding, tar both groups with the same brush. Obviously, they feel threatened by those who they see are unjustifiably attacking their beliefs. Yet for many theists, especially the religious fundamentalists, the very phenomenon of non-belief itself is considered a threat to their culture, so they lash out at all unbelievers indiscriminately. I don’t know whether explaining the difference to theists would make a difference in their understanding and tolerance of non-belief as a whole. But if by utilizing this approach, we can get at least a few of them to realize that not all of us godless folks are their enemies, it would be a start. And as I see it, that’s worth the effort.
