unbeliever (part of speech: noun)
- I am not a pessimist- at least, I try not to be. - "The New Tenant", E. Phillips Oppenheim.
- And which of us is not more or less of a Pessimist nowadays? - "Outlines of a Philosophy of Religion based on Psychology and History", Auguste Sabatier.
- Ellis was not the man to feel a malicious delight in the misfortunes of another, nor was he a pessimist who welcomed scandal and disgrace with open arms, as confirming a gloomy theory of human life. - "The Marrow of Tradition", Charles W. Chesnutt.