We live in a society where preconceived notions about religious schools and indoctrination are many but the rules regarding a non-denominational education are strict. It is of great importance to get a better understanding of religious schools and their effect on the pupils that attend them. The aim of this study is to analyze whether or not the compulsory religious education on a private religious school in the south of Sweden is non-denominational. In order to get a greater understanding of the impact on the pupils’ religious identity, Henri Tajfel’s theory of social identity is used. A total of eight observations, three interviews and collected materials such as previous tests regarding Islam, Christianity and Judaism have been gathered and discussed with the help of Tajfel’s theory and other previous research. The results show that some denominational elements could be found in the compulsory education and that the school at hand had an impact on their pupils’ Muslim identities. With these results, my ambition is that teachers that read this study will be more reflective and critical of their own teaching. It is possible that some teachers do not notice that their own religion or beliefs are shining through their teaching and could potentially effect the pupils. However, if teachers start to reflect upon their teaching and the impacts it could have on a pupil these denominational elements could be prevented.