This article contains the results of how a selected group of Finnish upper secondary students understand Lutheranism. The data consisted of 63 students' responses to a writing task together with complementary interviews of 11 students. The outcomes of phenomenographic analysis of variation in the students' understanding of Lutheranism are presented in five hierarchically ordered categories. The implications for religious education are discussed in terms of what teachers could learn from differences in students' understandings of the subject matter in order to enhance their learning of it. (Contains 1 table.)