The article analyzes political mobilization toward the establishment of an independent Ukrainian national church. Ukraine had three Orthodox Churches, the largest of which is under the jurisdiction of the Moscow Patriarchate, while the others lacked ecclesiastical legitimacy. On 11 October 2018, in a dramatic decision with geopolitical consequences, the Kyiv Patriarchate received ecclesiastical recognition from the Istanbul-based Ecumenical Patriarchate. Drawing on sixteen interviews with key clergy, academics, and policy practitioners working on church-state relations in Kyiv (Kiev), a literature review, and online data from Bulgarian, Greek, Polish, Romanian, Russian, Serbian and Ukrainian sources, the article argues that the conflict in Donbas has been a key factor in the national and international mobilization toward autocephaly. This article demonstrates that in Eastern Orthodoxy, national churches perform state-like functions in three areas, namely establishing diplomatic channels of communication; mobilizing the faithful at national and international levels; and advancing human security discourses on violence, survival, and tolerance.