This paper examines how sacred boundaries materially organize choral performance, gendered participation, and musical structure in the Celestial Church of Christ (CCC) Yemetu, Ibadan, Nigeria. While scholarship on African Indigenous Churches has emphasized theology, ritual symbolism, and institutional history, comparatively little attention has been given to how doctrinal regulations shape musical practice at the level of rehearsal, sound production, and ensemble coordination. Drawing on ethnographic fieldwork and musicological analysis, this study argues that sacred boundaries function as performance technologies that structure spatial arrangement, authority, vocal distribution, and liturgical sequencing. Regulations governing altar access, hierarchical rank, and menstrual purity directly influence leadership patterns, rehearsal planning, cantata execution, and harmonic balance. Rather than operating solely as constraints, these boundaries generate adaptive musical strategies, including flexible part redistribution, anticipatory rehearsal culture, and spatially negotiated ensemble interaction. Hymnody and liturgical flow further reinforce sacred order by sonically marking purity, hierarchy, and divine authority. Engaging theories of the sacred and profane alongside ethnomusicological approaches to music as social action, the paper demonstrates that sacred order in African Indigenous Christianity is not only believed or symbolized but acoustically produced and continually reproduced through choral practice. By foregrounding the intersection of gender, embodiment, and musical form, this study contributes to broader debates on religion, performance, and power while advancing a music-centered understanding of how ritual regulation becomes audible in lived worship.