Okay, that's how you define it.
However, I dispute that definition. First off, atheism by itself is nothing more than a lack of belief in deities; while I suppose it's possible to promote the lack of belief in deities, it's not something that makes a lot of sense. It's like promoting a lack of belief in leprechauns, or in unicorns, or in faeries.
Second, it's possible to be secular and atheist, just as it's possible to be secular and religious. There is no reason this shouldn't hold true for governments as well as for people. That means you can have a government which is atheistic but doesn't have a state policy on it, and you can have a government which is religious but doesn't have a state policy on it. Furthermore, it's possible to have a state policy on religion (and thus atheism) without being totalitarian. England falls into that category, for example, since it does have a state church but doesn't really do much about it.