"Secularism and Church Music" is an interdisciplinary study that examines the effects of the secularization process on perceptions of religion and church music through the case of the Netherlands. Within the theoretical framework of secularism and post-secularism, the book explores how changing social structures in Western Europe have transformed religious practices and modes of musical expression. Based on qualitative field research conducted over the last twenty years in Protestant, Catholic, and Evangelical churches in the Netherlands, the study analyzes the transformation of church music in terms of repertoire, instrumental usage, performance practices, and congregational participation. In this context, music is considered not only as an element of worship but also as a significant component of cultural heritage and the construction of social identity. The work offers an original contribution for researchers seeking to understand the relationship between religion, music, and social change.