Thank you. Yet, αγνωστικιστής is the noun form but the translation feels like there should be an adjective in place instead. This more looks like a nom.noun + nom.noun form to me, but I might be missing something else for sure.
It's still useful to know about what is called "alpha privative (α-/a-)" which is found in many foreign words of Greek origin. This is also a reminder that "agnostic" comes from "gnosis=knowledge".