A country with religious and cultural diversity, such as Indonesia, necessitates the cultivation of a moderate attitude, particularly through character education. This study aims to identify effective learning steps to develop a sense of religious moderation in high school students in Islamic Education. To achieve this goal, action research was chosen as the research design, as it provides a framework for addressing pedagogical issues and finding solutions. The study involved 50 students from two high schools in Bandung, West Java, Indonesia, conducted in three research phases: pre-action, action implementation, and action evaluation. Data collection was accomplished through surveys and semi-structured interviews, allowing for data analysis utilizing two approaches: qualitative analysis employing content analysis and quantitative analysis involving descriptive statistical analysis and effectiveness testing. The study outlines five stages of learning, which are summarized in the acronym PEACE: Promotion, Elaboration, Actualization, Communication, and Evaluation. These steps improved religious moderation attitudes in four aspects: maintaining harmonious relationships with other people, respecting people’s differences, demonstrating tolerance and rejecting fanaticism, and thinking ahead. To conclude, the PEACE method proved highly effective in cultivating religious moderation attitudes, with the average N-Gain score exceeding 0.7 at 0.7653 and an N-Gain percent of 76.7%. The development of religious moderation attitudes from the perspective of other religions can be explored in future research.