(of a) person who believes that nothing can be known about the existence of God

person unsure that god exists

a person who sees little or no good in anything and who has no belief in human progress (especially showing this by being sarcastic)

nonbeliever

(of) a person not of the Jewish race

nonbeliever

concerning pantheism ( = (the belief in) the theory that God is in everything and that everything is God)

person who does not believe in an orthodox religion

a person who doubts the truth of a particular claim, theory, belief etc

detractor