The Knowers
You may hear someone say "Gnostics think they possess secret knowledge and believe they have everything figured out."
It's not that simple.
The word Gnostic comes from the ancient Greek gnōstikós, meaning “knowing,” “able to know,” or “pertaining to knowledge,” from gnōsis, meaning “knowledge.” So “Gnostics” can reasonably be rendered as “the knowers.”
But they weren't talking about knowing in the sense of accumulating intellectual information. In many of the traditions we call Gnostic, gnosis refers to a direct or experiential knowledge of the divine that no external authority can simply grant you or take away. No one can prove or disprove such an experience. It's simply not that kind of thing. God is too great for ordinary language and cannot be reduced to intellectual concepts. We can encounter or experience the divine, but thinking about God is not the same thing as knowing God. In ancient Hebrew and Greek religious contexts, “knowing” could also carry a deeply experiential and relational meaning rather than referring only to intellectual understanding.
This is also why I think a lot of people get the “mystery” part of Gnosticism wrong. Gnosis does not necessarily mean claiming to have solved the mystery. Rather, a Gnostic may claim to have encountered the Mystery directly. The Gnostic experiences the divine; they aren't necessarily outlining an intellectual diagram of God.
So, the Gnostic isn't someone who claims to have the answer. The Gnostic is someone who has encountered what cannot be reduced to an answer, or remains open to such an encounter.