There is a common misconception that agnosticism lies somewhere between theism and atheism.

In truth, they are not comparable terms. Theism, and atheism, are about belief. Gnosticism, and agnosticism, are about knowledge.

Agnosticism is essentially just saying "we do not (or can not) know". However, that has no bearing over whether one actively believes in a deity.

For example, one could say, "I believe in a god, but don't think we can truly prove his/her existence", and you'd be an agnostic theist. On the opposite side, "I don't believe in a god, but don't think we can truly prove they don't exist" is an agnostic atheist.

There are, of course, the much less reasonable viewpoints on both ends, as well: "There is definitely a god," "there definitely is no god". Those would be gnostic theist, and gnostic atheist, views.