Agnostic
Part of speech: noun
Definition: A person who holds to a form of agnosticism, especially uncertainty of the existence of a deity.
Part of speech: adjective
Definition: Of or relating to agnosticism or its adherents. Doubtful or uncertain about the existence or demonstrability of God or other deity. A software component (or other entity) that is unaware or noncommittal regarding the specific nature of the components with which it interacts; polymorphic; modular; pluggable
Example sentence: I'm an optimistic agnostic. I think the second we die, within a matter of seconds, everybody else arrives, and that's the party, and you live your hell on earth.
Doubter
Part of speech: noun
Definition: One who doubts.