Purpose of the study: This study aims to examine changes in non-Muslim students’ perceptions and understanding of Islam after participating in Islamic Religious Education (PAI) at Bumiayu 1 State Senior High School, Kabupaten Brebes, particularly across the dimensions of aqidah, syariah, and akhlak. Methodology: A qualitative descriptive field research design was employed. Data were collected from six non-Muslim students and one Islamic Religious Education teacher through direct classroom observation, semi-structured interviews, and documentation. Observation and interview guidelines were used as research instruments. Data were organized, reduced, presented descriptively, compared across sources, and verified before conclusions were drawn. Main Findings: Participation in Islamic Religious Education was associated with increased understanding of several Islamic teachings, particularly in the aqidah dimension, including Allah, Asma’ul Husna, the Qur’an, believers’ characteristics, and the Hereafter. Selected akhlak teachings also became better understood, while changes in syariah were limited. However, perceptual changes varied according to students’ attention, engagement, and exposure to specific learning materials. Novelty/Originality of this study: This study advances existing research by examining Islam through the perceptions of non-Muslim students who directly encounter Islamic Religious Education in an ordinary Indonesian school setting. It identifies differentiated changes across aqidah, syariah, and akhlak, demonstrating that religious exposure does not produce uniform perceptual change and that student engagement is an important factor in religious understanding.