Millennials are the most analyzed and populous generation in the United States. Collectively, they have been slowly re-shaping the American culture. Protestant Millennials, a subset of this generation, have been ruffling feathers in their local churches. Many, who once regularly attended, are leaving. Unwise responses by local church leaders to their young parishioners’ doubting habits significantly contributed to the departure. This study pursued a sample of college-aged Protestant Millennials to know them in a psychological sense. The intentions were twofold: to discover social personality traits that predict their doubting practices and to develop practical and proactive relational strategies for local church leaders. Self-report data on personality features and doubt phenomena were obtained from 532 religiously committed undergraduates in the United States. Results from multivariate regression procedures revealed three social personality dispositions contributed to the prediction of the doubt constructs. Implications and applications of the findings are discussed.