In personal life, people tend to experience conflict, both personal and interpersonal, and often this is between groups. This conflict arises due to a tendency toward aggressive attitudes, both personal and social. One aspect that causes conflict is differences in customs and cultures. The students of the Periago Theological High School come from various ethnicities and cultures and cannot be separated from conflicts, especially interpersonal conflicts. Thus, this study aims to find out how the state of interpersonal conflict is related to the tendency to be aggressive due to the differences in the customs and cultures between students. The research method used was a quantitative method. While the results of this study are based on interpersonal conflicts between students that occur in circumstances where differences in customs and culture affect students, there is also tendency to behave aggressively due to a lack of understanding of Christian religious education among college students. In addition, there is a strong relationship where interpersonal conflict with tendencies toward aggressive behavior greatly affects students if the Christian religious education that students receive is well understood.