Jazz in Worship and Worship in Jazz The musical language of Liturgical, Sacred, and Spiritual Jazz in a postsecular Age. Abstract The aim of this dissertation is to identify musical elements that contribute to the generation of religious meaning in jazz performance and to explore how religious experience can inspire jazz composition. In this study, the history of jazz, specifically tailored to the aspects of my inquiry is imbricated with relevant theories and musical interventions from my own artistic practice in composition and performance. In addition to artistic research through my own practice as a performer and composer, the transdisciplinary fields of musicology, music theory, neurology, history of religion, and theology provides further critical tiles in the knowledge-mosaic constructed by this study. Using my own artistic practice as my primary research method, my thesis investigates distinct intrinsic and extra-musical elements that help to create a typology of religiously inspired jazz, grounded in historical reference works. Twenty-five of my own compositions following this typology are submitted with this thesis and are analyzed in the three main chapters. The final chapter (Imagine) summarizes conclusions of the main chapters and includes a brief evaluation of the research process. Conclusions from the thesis include (i) defining six distinct ways of expressing religious belief in jazz, (ii) demonstrating that the extrinsic meaning of religiously inspired jazz changes when placed within a liturgical dramaturgy, and (iii) generating new postsecular perspectives on jazz. Another concrete result of this thesis involves revisiting George Russell´s Lydian Chromatic Concept as a basis for my own compositions. The practice-based adaption and exploration of Russell´s theory opens new ways of understanding how his musical philosophy builds a bridge between Western classical sacred music and jazz. Finally, this thesis also raises new areas for further research such as microtonal and twelve-tone tonality in jazz, temporal concepts in jazz composition and improvisation, and the embodiment of Christian faith through music as an extension of the institutional church in society. Keywords: jazz and religion, jazz liturgies, George Russell, Spiritual Jazz, Sacred Jazz, Liturgical Jazz, postsecularity in the arts, twelve-tone tonality in jazz