Weak and strong atheism
Main articles: Weak atheism, Strong atheism
Weak atheism (also called negative atheism) is the lack of belief in the existence of deities, without a commitment to the necessary non-existence of deities. Weak atheism contrasts with strong atheism, which is the belief that no deities exist, and theism, which asserts that there is at least one deity. The weak atheist generally gives a broad definition of atheism as a lack or absence of evidence justifying a belief in any deity, which defines atheism as a range of positions that entail non-belief, disbelief, doubt of theism.
Strong atheism, sometimes called positive atheism, hard atheism or gnostic atheism, is the philosophical position that no deity exists. It is a form of explicit atheism, meaning that it consciously rejects theism. It is contrasted with weak atheism, which is the lack or absence of belief in deities, without the additional claim that deities do not exist. The strong atheist positively asserts, at the very least, that no deities exist, and may go further and claim that the existence of certain deities is logically impossible.
While the terms weak and strong are relatively recent, the concepts they represent have been in use for some time. In earlier philosophical publications, the terms negative atheism and positive atheism were more common.[5]
http://en.wikipedia.org/wiki/Athiest
*********
Do they passively practice it? For whatever you define as non-actively, that is.
Hmm... I guess I'd say I was thinking that they self-identify as X but that is the extent of their involvement.