We present the case of Michael, a prospective high school biology teacher, to explore the implications of teacher resistance and avoidance to the topic of evolution. This case is drawn from a year-long qualitative research study that examined Michael's process of learning to teach high school biology and describes how his avoidance of evolution in his own education led to further disengagement with evolution in his methods coursework and in his student teaching practice. Paradoxically, his high academic abilities obscured substantive knowledge gaps about evolution, and his content knowledge regarding evolution did not appear to improve as a result of his student teaching experience. Kohl's concept of "not-learning" is useful in understanding Michael's avoidance of learning evolution. His use of the discourse of evolution in coursework and in student teaching activities also helped to obscure his opposition to learning evolution. We present an argument that proficiency for teaching biology means not only tolerating evolution as a topic to be covered in class but also advocating for evolution as a foundational theme in the discipline. This research has implications for both the admissions process and curriculum of biology teacher preparation programs.