This research paper is dedicated to exploring the mutual influence of religion and ethnic processes in the multicultural societies of the Caucasus, which stand on secular values. Firstly, it explores transformation of religion in a new ethno-cultural environment and determines the main features of the vernacular religion, which is a product of historical process. In other words, the paper also tracks the adaptation process of religions in the Caucasus communities, both Christian and Muslim from a historical perspective. The second part of the paper considers a contemporary product of those religious and ethnic processes and their impact on identity formation. Moreover, it examines acculturation in multicultural societies of the Caucasus, as a specific type.