Christianity survived here until the beginning of the 7th century, when the Slavs, as vassals of the Avar and Obra tribes, came as far as south and west as the Adriatic Sea.
In much same way as the pagan barbarians had, they destroyed all the towns and Christian temples, such that all traces of civilization and Christianity were wiped out, as if they never existed.
The best evidence for this is the spread of Christianity among the Slavs in the 9th century, during the time of the Byzantine King Vasili of Macedonia who sent Cyril and Methodius to perform their missionary effort as if Christianity had never been in these areas before.
However, with the acceptance of Christianity, many of the rituals from the earlier pagan religion were maintained, which survived through the Middle Ages. Thus Bosnia was never a place which was firm in its religion, and therefore it became a crossroad for sect of those branded as heretics because they did not fit into the Orthodox Christian or Catholic Christian religion.
In the second part of the 9th century, Bosnia was a part of the kingdom of Duklja and Bosnian Church was under auspices of archbishop of the region of Bar (south of Dubrovnik, in Montenegro).
In the 12th century Bosnian Banovina was established, which was periodically dependent on Hungary. Its capital was the town of Visoko, with the St. Peter’s cathedral of the parish of Vrhbosna, mentioned in records dating back to 1379 A.D. It has been established that this was located at the place Koševo stream flows into the Miljacka river.
In 11th and 12th century Roman-style columns were discovered in the area of the present Skenderija which might be the remains of cathedral. Due to the strengthening of the Bosnian Church, considered heretical by Catholic Church, the Bishop’s seat was moved to Djakovo in Slavonia (north of the northern border of Bosnia).
In medieval Bosnia there were no significant settlements where craftsmanship and trade could develop. There were smaller fortified tows with living quarters made of wood, which were frequently destroyed in the feudal conflicts, forcing the inhabitants to take refuge inside the fortifications.
With the division of Christianity into Catholicism and Orthodoxy, the line between them running from Budva on the Adriatic to the Drina and along the Drina to the Sava River, this left the claim of the Sarajevo valley as belonging to the Catholic Church. Evidence for this is supported by the records of the Ottoman Turks – that all churches and monasteries located west of the above-mentioned geographical lines were Catholic, while the Orthodox were to the east.
On the other hand, the Bosnian Church or heretical sect did not leave any trace in the form of temples or cathedrals, because they did not build such structures. The only material traces we have of their presence are the monumental tombstones – the „Stećci“ – of which there remain more than 40 thousand. Their locations serve as an indication of where the Bosnian Church dominated. It was supposed that this church was part of the Bogumil Manichan sect came from Bulgaria.
Stećci in front of the National Museum
Manicheism is named after Manes (also known as Minacheus) (216 – 276 A.D.) – a Persian Bebylonian scholar and religious reformer who wanted to unite the theachings of Zarathustra, Buddha, and Jesus into a Gnosticism. He borrowed the dualism principle of good and evil from Persian Mazdaism, took the principles vegetarinism and asceticism from Buddhism, and the teachings of Paul from Chiristianity.
This teaching spread around Europe under different names. And while these heretical movements in France and Italy were wiped out by the Inquisition, in Bosnia and Herzegovina, the Bosnian Church co-existed as a leading religious sect together with Catholicism, until the Ottoman occupation when the Bosnian Church disappeared and a gradual conversion to Islam occured.
The development of Mithraism during Roman period no doubt had a significiant influence upon these developments.