To assert agnosticism is to be an atheist; because agnosticism denies the centrality of God.
If you believe yourself agnostic but do not realise you are actually an atheist; it can only because you have not fully thought-through the implications; or aren't being honest with yourself.
To assert agnosticism is usually a way of trying to avoid what someone regards unpleasant, boring, inconclusive, futile arguments - to change-the-subject. But this is only possible to one who has already decided that the question of God is unnecessary, irrelevant, unimportant, even destructive.
There are no real agnostics.