The article analyzes, based on expert reviews, public speeches, articles, as well as previously unpublished materials, the position of the professor of church history at the St. Petersburg Theological Academy Alexander Ivanovich Brilliantov (1867-1933) on the nature of church authority and the consequences resulting from this in the church-state relationship. The ideal model of church- state relations, considered by scholars, is described, as well as his criticism and opinion on the historical forms of church governance and the relationship between the Church and the state. A conclusion is drawn about the special position of A. I. Brilliantov: on the one hand, he saw the foundation of church governance as democratically understood collegiality and was opposed to “Caesarapapism”, which he attributed to the legacy of the “pagan world”, but, on the other hand, it was from the principle of collegiality that he advocated for the participation of the state in the person of the Emperor in church life, up to the reso