Interpreting the axioms of Holy Scripture, the spiritual ideas of the era of high Scholasticism and the texts of St. Francis of Assisi, Messiaen chose the choir as the instrument necessary for interpreting the spiritual meaning of the work. In the finale of the opera, the non-verbal and verbal parts of the invisible and visible chorus interact, acting as a commentator, participant in the action / "collective character" and, finally, the protagonist. Drawing on the achievements of modern theological thought and developing the tradition of Claudel's theatrical liturgy, Messiaen embodied in the opera's finale a set of spiritual ideas relevant to the modern era. These are the ideas of death as the liberation of the soul "from prison," the transformation of the soul of a saint under the influence of grace, spiritual light, praise of God in creation, spiritual joy, and the connection between man, the world, and God. The vectors of the hermeneutic reconstruction of the artistic idea of Messiaen's opera were translations into Russian of religious, philosophical and theological studies contemporary to the composer, revealing the meaning of the main spiritual ideas of the era of high scholasticism, as well as translations of texts by St. Francis of Assisi. The research tool is a musicological analysis of the musical text de visuale and other paintings of Messiaen's opera. This article highlights for the first time the interpretation of the spiritual ideas and poetic texts of St. Francis of Assisi in the finale of Messiaen's opera through the prism of the metamorphosis of the choir and its functions, as well as the connections of the "Franciscan Scenes" with the tradition of Catholicism by P. Claudel. The finale of Messiaen's opera, which includes a spiritual super-idea unified with Claudel's mystery, contains a complex of ideas of Franciscan spirituality. In the finale of the opera "St. Francis of Assisi. Franciscan scenes" Messiaen interpreted the following spiritual ideas: death as the liberation of the soul "from prison", inner spirituality, the transformation of the soul of St. Francis of Assisi under the influence of grace, truth, immortality of the soul, spiritual light, praise of God in creation and spiritual joy. Revealing the composer's interpretation of the verses of Holy Scripture, the spiritual ideas of the era of high Scholasticism and the texts of St. Francis of Assisi, the choir acts as a commentator, participant in the action, a "collective character" and, finally, a protagonist. The stage functions of the choir are variable.