Bosnian Church is an institution that grew out of a Catholic monastic order which broke, probably in the middle of the thirteenth century, with international Catholicism. It could be considered as the first protestant church in Europe. Documentation from the fourteenth century and especially from the fifteenth, shows Bosnian Church, under its own bishop called djed (grandfather), to be a monastic institution. No sources suggest that any change of theology occurred at the time it broke with Rome and almost all later local and Ragusan (Dubrovnik) sources on the Bosnian Church suggest it was mainstream in its theology throughout its existence.
 

Throughout history, the Bosnian Church retained both its more-or-less catholic theology - though it used Slavic language - and its monastic character. Its clergy resided in monasteries called hiže (sing. hiža, meaning house). The clergymen bore the title of Christians (Krstjani) - usually rendered as Patarini in Ragusan Latin language sources. The head of a monastery (hiža) was often called a gost (guest). The djed and his council of twelve strojnici, chiefly composed of gosts, provided that overall supervision was there. Their monasteries were not found throughout Bosnia but were clustered in the center of the state, extending east to the Drina river and south toward and beyond the Neretva river, with a few on the lands of the Kosača family in Herzegovina. Some of their monasteries served as hostels for travelers and were used by Ragusan merchants. The Bosnian Church never established a secular clergy or any sort of territorial organization. The institution seems to have consisted only of a series of scattered monastic houses, usually in villages, each having a relatively small number of monks. Probably peasants could go to these monasteries for services. Gravestone inscriptions at least show that krstjani participated in the burials of laymen.
 

The Bosnian Church was tolerated by the state even after the 1340s when a Franciscan mission was established inside Bosnia and the rulers became Catholic. The tolerance, or indifference, of Bosnian rulers and nobility regarding religious issues is a prominent feature of medieval Bosnia. The Bosnian Church did not play a major role in the state and was not a state Church. For most of its existence it had no political role in the state. In fact a political role can be shown chiefly in the early fifteenth century - particularly between 1403 and 1405 - when the djed was an influential advisor at court. His influence then was probably owing to the particular sympathy for his Church on the part of King Ostoja, who most probably was an adherent of the Bosnian Church and the only post-1340 ruler who was not a Catholic. This djed's influence may also have been owing to his particular qualities as an individual. Since Bosnia's rulers from the 1340s -except Ostoja - were all Catholics, it is not surprising that the Bosnian Church was not a major state institution.
 

The Church's supporters did include the major nobles; Hrvoje Vukčić, the Radenović-Pavlovići, Sandalj Hranić and Stefan Vukčić, and Paul Klešić were among its adherents. For most of this nobles the services performed for them by the krstjani were entirely religious. Krstjani also usually served as diplomats or mediators in quarrels.
 

Few Bosnian Church texts survive. Of these, most important are the surviving pages of Gospel manuscripts. Some are beautifully illustrated: the Radoslav Ritual, the Hval gospel, Tepčija Batalo's Gospel. The last will and testament from 1466 of Gost Radin - a Bosnian Church leader and important diplomat, first for the Pavlovići and later for Stefa Vukčić - survives. A letter written by the djed in 1404, concerning the dispute between the king and the nobleman Paul Klešić, also provides some information on the Church.

The only contemporary sources describing dualists in Bosnia are foreign (chiefly Italian). They come from the inquisition or the papacy. The papal sources date almost entirely after the late 1440s. Most of these sources simply call the Bosnian dualists they describe "Bosnian heretics". These sources probably refer to a separate and small dualist current also existing in Bosnia that derived from Dalmatian dualist Church (Ecclesia Sclavonia), some of whose members fled to Bosnia at the time of Ban Kulin. This heresy, attracting few followers but seemingly surviving in Bosnia until the end of the Middle Ages, throughout remained a separate institution, distinct from the Bosnian Church.
 

One of Bosnia's main differences from the other Balkan lands lay in the fact that no Church had a central role in the life of the state or of the nobles. Noblemen were distributed among all three faiths: Bosnian, Catholic and Orthodox. Bosnia was the only country were membership in the community was not dependent on a common religion. And formal religion doesn't seem to have been important to the Bosnian nobles. They freely changed faiths and freely associated and allied with figures of different faiths. Thus tolerance, or rather indifference, marked Bosnian religious issues until the very end of the state, when papal pressure finally forced King Stefan Tomaš to turn to persecutions.
 

The Catholic Church in Bosnia was represented solely by a limited number of Franciscans, who were also limited to a small number of monasteries. The Catholics also had no territorial organization in Bosnia. The Catholic bishop, the titular Bishop of Bosnia, resided outside the state in Djakovo in Sclavonia (Croatia) and played no role in Bosnia, possessing only theoretical authority there.
 

The orthodox Church, existing in Hum and the region west of the Drina, was not a major institution in Bosnia either. They did have a major bishop, a metropolitan, at Mileševo, a famous Orthodox monastic center . Sandalj and Stefan Vukčić at one time or another had Orthodox wives who took interest in their Church. orthodox clerics were not found at the royal court or in most of Bosnia. And the number of Orthodox clerics in Hum and the Drina region, as a whole, does not seem to have been large.
The existence of three faiths in Bosnia prevented the development of a national church and blocked any Church institution from acquiring a major role in the state.