Research has previously examined the role of the epistemological background of students in accepting or rejecting the theory of evolution. In this study, the participants were 11 undergraduate biology major students in a private university in Beirut, Lebanon. We collected data through semi-structured interviews, and we extracted the patterns regarding how they perceived tentativeness, what constituted acceptable evidence for them to accept the theory of evolution and the role of religion in their lives. Our findings indicated that, unlike their professor, students uncertain about the theory or rejecting it did so due to the tentative nature of science. They also rejected historical evidence as valid evidence in science, struggled to form a cooperative relationship between evolution and religion and refused common descent because they considered humans as superior organisms. We discuss the implications of those results for curriculum and instruction.