The Christian teacher as a guide and mentor is not a teacher who focuses on academic achievement, but rather guides and assists students to become like Christ and responsible individuals. However, the reality is that many teachers still adopt traditional learning, neglect other skills, and distance themselves from Biblical truth. This article presents the role of the Christian teacher as a guide and mentor in the context of the relevance of science to the environment, especially Ki Hajar Dewantara's "Three Wall Classroom" concept through authentic learning based on Biblical insights using a literature review. As a result, Christian teachers as mentors and guides are able to create holistic learning, meaningful and relevant learning, collaborate with reality, and bring students to the knowledge of God. In conclusion, the Christian teacher as a guide and mentor in the "Three Walls Classroom" through authentic learning is to center learning on Christ, motivate student development in all aspects, and become an agent of restoring students' relationship with God. As a suggestion, a teacher must understand the calling as a ministry. For future writers, it is suggested to dig deeper into educational issues and add relevant evidence or data.