This study seeks to investigate the capacity of religious education within a denominational setting to contribute to an authentic inclusion. The understanding of an authentic inclusion that underpins this study recognises and engages with the complexities of a pluralism, in which there are often incompatible and contested world views on the nature of the ultimate order-of-things, by providing opportunities and encounters for true communication and dialogue. In reviewing the literature differing, and at times conflicting, expectations regarding the purpose, nature and scope of RE in post-primary schools, as held by the Irish State and the Catholic Church, is identified. These conflicting expectations have emerged from the historical influence which the Catholic Church has had on Irish education as a whole, and on the provision of RE in particular, and the subsequent efforts of recent governments to align practice more closely with European educational policy. This qualitative bounded case study which investigates the role of religious education in an increasingly diverse educational landscape is scaffolded by two key pillars: the voice of students and the voice of Religion teachers. Firstly, the study provides an insight into how senior-cycle students of different religious and secular worldviews experience religious education within a denominational context. Secondly, the perspective of the Religion teacher is investigated with particular attention paid to how teachers experience the delivery of religious education in an increasingly diverse environment. The study involves an exploration of diversity in terms of religious belief, intra-religious diversity and secular worldviews. In doing so the study foregrounds a diversity of perspectives and puts these in dialogue with literature from the academy as well as State and Church policy. The research findings suggest that students of different belief backgrounds experience religious education at senior-cycle in different ways. Further, a dichotomous understanding of what the purpose, nature and scope of religious education ought to be exists between the participating teachers and students. Where these different perceptions collide, it is students with minority religious and secular worldviews who are most impacted upon. A consensus, however, regarding the potential the subject has to provide a pluralist perspective is also evident. Finally, the research draws on the work of Jackson, Ipgrave and Cullen to provide a way forward towards an authentically inclusive experience of senior-cycle religious education, which necessitates a dialogical, reflexive and critically engaging experience for students and teachers of all religious and secular worldviews.