Abstract: The lack of unity between the Churches prevents them from fully and effectively bear the Christian testimony in public. During the second Christian millennium, the three major Christian traditions – Roman Catholic, Protestant and Orthodox – have come to take distance from the territorial principle of ecclesiology, according to which the Church must be one “in every place”. Since the Crusades (1095-1204), the Roman Catholic Church had started to establish Latin Patriarchates as an alternative to the already existing Oriental Local ones and, thus, created the ecclesiological problem of co-territoriality (1099). Gradually, and especially since the introduction of “Uniatism” (1596), Catholic ecclesiology came to allow churches of different ritual traditions to exist within a single territory. This antiecclesiological and anticanonical conviventia created a new epoch for the Church, an epoch which is obviously post-ecclesial. Therefore, Protestantism, emphasising the “confession of the faith” which created the ecclesiological problem of confessionalism (1517), as the foundation of the Church, came to admit the co-existence (co-territoriality-conviventia) in a single place of churches of different confessions. As for Orthodoxy, it did not consider the interruption of communion with the Western Church (1054) as a full schism, and did not, therefore, attempt to create anything resembling an alternate “Orthodox Patriarchate of Rome”. But from the 19th century, the emigration of Orthodox Christians to regions outside the traditional territory of their respective churches, together with the growth of ethno-phyletism (1872), led to the creation of multiple Orthodox dioceses (co-territoriality-conviventia), based exclusively on ethnic criteria (multi-jurisdiction), in full communion with each other. National Orthodox Churches sometimes go so far as to claim a kind of extra-territoriality to enable them to minister to their compatriots abroad. This text conducts a research on the ecclesial-canonical problem of co-territoriality-conviventia through the three major Christian Ecclesiologies of the second Christian millennium: 1. The Ecclesiology of the Crusades (13th century); 2. The Ecclesiology of the Reform (16th century) and 3. The Ecclesiology of Ethno-Phyletism (19th century).

Keywords: co-territoriality, post-ecclesiality, anticanonical conviventia, confessionalism, ethno-phyletism