[3] The monumental tombstones called stećak that appeared in medieval Bosnia, as well as Croatia, Serbia, and Montenegro, are sometimes identified with the Bosnian Church.

[4] Lying in-between, the mountainous Bosnia was nominally under Rome,[4] but Catholicism never became firmly established due to a weak church organization[4] and poor communications.

Following the abjuration of Bilino Polje, Kulin succeeded in keeping the Bosnian Diocese under the Ragusan Archdiocese, thus limiting Hungarian influence.

In order to conduct a crusade against him, the Hungarians turned to Rome, complaining to Pope Innocent III that the Kingdom of Bosnia was a centre of heresy, based on the refuge that some Cathars (also known as Bogomils or Patarenes) had found there.

To avert the Hungarian attack, Ban Kulin held a public assembly on 8 April 1203 and affirmed his loyalty to Rome in the presence of an envoy of the Pope, while the faithful abjured their mistakes and committed to following the Catholic doctrine.

In 1234, the Catholic Bishop of Bosnia was removed by Pope Gregory IX for allowing supposedly heretical practices.

This decision provoked the schism of the Bosnian Christians, who refused to submit to the Hungarians and broke off their relations with Rome.

[13] In that way, an autonomous Bosnian Church came into being, in which many scholars later saw a Bogomil or Cathar church, whilst more recent scholars such as Noel Malcolm and John Fine maintain that no trace of Bogomilism, Catharism, or other dualism can be found in the original documents of the Bosnian Christians.

Stjepan Kotromanić shortly reconciled Bosnia with Rome, while ensuring at the same time the survival of the Bosnian Church.

[16] Outsiders accused the Bosnian Church of links to the Bogomils, a stridently dualist sect of Gnostic Christians heavily influenced by the Manichaean Paulician movement.

[citation needed] Notable exceptions were when King Stephen Ostoja of Bosnia, a member of the Bosnian Church himself, had a djed as an advisor at the royal court between 1403 and 1405, and an occasional occurrence of a krstjan elder being a mediator or diplomat.

[citation needed] Hval's Codex, written in 1404 in Cyrillic, is one of the most famous manuscripts belonging to the Bosnian Church in which there are some iconographic elements which are not in concordance with the supposed theological doctrine of Christians (Annunciation, Crucifixion and Ascension).

This interpretation has been accepted, expanded and elaborated upon by a host of later historians, most prominent among them being Dominik Mandić, Sima Ćirković, Vladimir Ćorović, Miroslav Brandt, and Franjo Šanjek.

However, a number of other historians (Leo Petrović, Jaroslav Šidak, Dragoljub Dragojlović, Dubravko Lovrenović, and Noel Malcolm) stressed the impeccably orthodox theological character of Bosnian Christian writings and claimed the phenomenon can be sufficiently explained by the relative isolation of Bosnian Christianity, which retained many archaic traits predating the East-West Schism in 1054.