Seeing the reality, people around us often differentiate themselves from others, only because of different understandings about practicing Islamic teachings, resulting in disharmonious relationships between fellow Muslims. Even though each group has its own foundation in practicing its teachings, and even that has become a culture in its own right. This research was conducted to observe the change in self-concept of students from various organizational backgrounds after entering Muhammadiyah 2 High School in Yogyakarta. This study uses a qualitative approach with descriptive methods so that students' self-concept changes are well illustrated. The findings of this study show that students at Muhammadiyah 2 Yogyakarta High School can already understand and accept their friends even though they are of different cultures (ethnicity, different understanding), but in terms of subject attitudes towards their friends who are in brawl, there are still many subjects who do not respect their environment. But in terms of prayer procedures, only 9 people changed and 21 people did not feel a change in praying. This proves that not all students experience changes in understanding and carrying out religious teachings.