As a deep expression of the human spiritual world, religious mysticism has a deep internal relationship with music art. This paper takes cello music as the research object and explores how it maps and expresses the spiritual core of religious mysticism through musical language. Based on the theoretical basis, this study analyzes the compatibility between the transcendental and sacred characteristics of religious mysticism and the artistic characteristics of the cello with a wide range and mellow timbre, and reveals the interactive relationship between the two in the transmission of emotions and the creation of artistic conception. Through textual analysis and case studies, this paper finds that the mapping of religious mysticism in cello music is mainly reflected in two dimensions: first, the relationship between the theme of the work and religious stories and imagery, such as the musical presentation of the biblical narrative in the adapted version of Bach's Matthew Passion and the acoustic interpretation of divine wisdom in Bloch's Solomon; The second is the religious expression of creative techniques, including the symbolic meaning of harmonic colors, the ritual creation of melodic lines, and the echo of rhythmic patterns to religious chants. At the level of performance practice, the study further explores the interpretive role of performance techniques such as kneading, portamento, and velocity control on religious sentiments, and combines the interpretation cases of performers with religious backgrounds such as Casals to reveal the deep resonance between faith experience and musical expression. Through an in-depth analysis of works such as Hebrew Vespers and Unaccompanied Cello Suite, this paper argues that religious mysticism not only provides a unique theme for cello music, but also expands the depth and breadth of its spiritual expression. Research shows that the mapping and expression of religious mysticism in cello music is not only the continuation of cultural traditions, but also the driving force of artistic innovation. Future research can further focus on the integration and transformation of religious music elements in cross-cultural contexts, as well as the new possibilities of modern music technology for the expression of religious mysticism.