Why do several nonreligious people self-identify as agnostic and not as atheist? Beside epistemological differences regarding what is knowledgeable, we hypothesized that such a preference reflects (a) personality dispositions, that is, prosocial orientation, open-mindedness, but also neuroticism, (b) cognitive preferences, that is, lower analytic thinking, and (c) ideological inclinations, that is, openness to spirituality. In a secularized European country (Belgium), we surveyed participants who self-identified as Christian, agnostic, or atheist (total N = 551). Compared to atheists, agnostics were more neurotic, but also more prosocially oriented and spiritual, and less dogmatic. Strong self-identification as atheist, but not as agnostic, was positively related to analytic thinking and emotional stability but also dogmatism. Nevertheless, spiritual inclinations among both agnostics and atheists reflected low dogmatism and high prosocial orientation, and, additionally, among agnostics, social and cognitive curiosity. From a personality perspective, agnostics compose a distinct psychological category and are not just closet atheists.