https://en.wikipedia.org/wiki/Christianization#Czech_lands

Christianization of Europe (7th-15th centuries)[edit]

Great Britain and Ireland[edit]

In most of Britain, the native Britons were already partly Christianized by the time of the Anglo-Saxon settlement of Britain; it is not clear how thorough this process had been. Ireland, and parts of Scotland, had been converted by the Romano-British Christians, led by Saint Patrick. However, ecclesiastics of the time such as the British Gildas and later Anglo-Saxon Bede, criticized them for generally refusing to work at all for the conversion of the Anglo-Saxons, in fact many were absorbed into the religion and culture of the new settlers.

The conversion of the Anglo-Saxons was begun at about the same time at the far north and south of the Anglo-Saxon kingdoms in two unconnected initiatives. Irish missionaries led by Saint Columba based in Iona (from 563) and elsewhere, converted many Picts. The court of Anglo-Saxon Northumbria, and the Gregorian mission, who landed in 596, did the same to the Kingdom of Kent. They had been sent by Pope Gregory I and were led by Augustine of Canterbury with a mission team from Italy. In both cases, and in other kingdoms, the conversion was generally “top down”, with the royal family and nobility adopting the new religion first.

The Viking invasions of Britain and Ireland destroyed many monasteries and new Viking settlers restored paganism—though of a different variety to the Saxon or classical religions—to areas such as Northumbria and Dublin for a time before their own conversion.

Frankish Empire[edit]

The Germanic peoples underwent gradual Christianization in the course of the Early Middle Ages, resulting in a unique form of Christianity known as Germanic Christianity that was frequently some blend of Arian Christianity and Germanic paganism. The Eastern and Western tribes were the first to convert through various means. However, it would not be until the 12th century that the North Germanic peoples had Christianized.

In the polytheistic Germanic tradition, it was possible to worship Jesus next to the native gods like Woden and Thor. Before a battle, a pagan military leader might pray to Jesus for victory, instead of Odin, if he expected more help from the Christian God. According to legend, Clovis had prayed thus before a battle against one of the kings of the Alemanni, and had consequently attributed his victory to Jesus.^[7] The Christianization of the Franks laid the foundation for the further Christianization of the Germanic peoples.

The next impulse came from the edge of Europe. Although Ireland had never been part of the Roman Empire, Christianity had come there and developed, largely independently, into Celtic Christianity. The Irish monks had developed a concept of peregrinatio.^[8] This essentially meant that a monk would leave the monastery and his Christian country to proselytize among the heathens. From 590 onwards, Irish missionaries were active in Gaul, Scotland, Wales and England. During the Saxon Wars, Charlemagne, King of the Franks, Christianized the Saxons by way of warfare and law upon conquest.^[9][10]

Czech lands[edit]

Great Moravia and its successor state Duchy of Bohemia were founded by West Slavs in Central Europe in 9th century. The territory of Great Moravia was originally evangelized by missionaries coming from the Frankish Empire or Byzantine enclaves in Italy and Dalmatia since the early 8th century and sporadically earlier.^[11][12] The first Christian church of the Western and Eastern Slavs known to the written sources was built in 828 by Pribina, the ruler and Prince of the Principality of Nitra, although probably still a pagan himself, in his possession called Nitrava (today Nitra, Slovakia).^[13][14] The first Moravian ruler known by name, Mojmír I, was baptized in 831 by Reginhar, Bishop of Passau.^[15] Despite the formal endorsement by the elites, the Great Moravian Christianity was described as containing many pagan elements as late as in 852.^[16]

The Church organization in Great Moravia was supervised by the Bavarian clergy until the arrival of the Byzantine missionaries Saints Cyril and Methodius in 863, upon Prince Rastislav‘s request.^[17] Cyril developed the first Slavic alphabet and translated the Gospel into the Old Church Slavonic language.^[17] Foundation of the first Slavic bishopric (870), archbishopric (880), and monastery was the politically relevant outcome of the Byzantine mission.^{[citation needed]} In 880, Pope John VIII issued the bull Industriae Tuae, by which he set up an independent ecclesiastical province in Great Moravia with Archbishop Methodius as its head.^{[citation needed]} He also named the German cleric Wiching the Bishop of Nitra, and Old Church Slavonic was recognized as the fourth liturgical language, along with Latin, Greek and Hebrew.^{[citation needed]}

Bulgaria[edit]

After its establishment under Khan Asparukh in 681, Bulgaria retained the traditional Bulgar religion Tengriism and the pagan beliefs of the local Slavic population. In the mid-9th century, Boris I decided to establish Christianity as a state religion in Bulgaria. In 864, he was baptized in the capital Pliska by Byzantine priests. After prolonged negotiations with both Rome and Constantinople, he managed to create an autocephalous Bulgarian Orthodox Church and used the newly created Cyrillic script to make the Bulgarian language the language of the Church.

Christianity was challenged during the rule of his first-born son, Vladimir-Rasate (889-893), who decided to return to the old Bulgarian religion. Boris I, who had previously retired to a monastery, led a rebellion against his son and defeated him. At the counsel of Preslav in 893, his third son, Simeon I who was born after the Christianization, was installed on the throne and the capital was moved from Pliska to Preslav as a symbol of the abolition of the old religion. Simeon I led a series of wars against the Byzantines to gain official recognition of his Imperial title and the full independence of the Bulgarian Church. As a result of his victories in 927, the Byzantines finally recognized the Bulgarian Patriarchate.

Serbia[edit]

The Serbs were baptised during the reign of Heraclius (610–641) by “elders of Rome” according to Constantine Porphyrogenitus in his annals (r. 913–959).^[18]

In 733, Leo III attaches Illyricum to Patriarch Anastasius of Constantinople.^[19]

The establishment of Christianity as state religion dates to the time of Eastern Orthodox missionaries Saints Cyril and Methodius during Basil I (r. 867–886), who baptised the Serbs sometime before sending imperial admiral Nikita Orifas to Knez Mutimir for aid in the war against the Saracens in 869, after acknowledging the suzerainty of the Byzantine Empire. The fleets and land forces of Zahumlje, Travunia and Konavli (Serbian Pomorje) were sent to fight the Saracens who attacked the town of Ragusa (Dubrovnik) in 869, on the immediate request of Basil I, who was asked by the Ragusians for help.^[20] A Serbian bishopric (Diocese of Ras) may have been founded in Stari Ras in 871 by Serbian Knez Mutimir, confirmed by the Council of Constantinople in 879–80.^[21]

The adherence is evident in the tradition of theophoric names in the next generation of Serbian monarchs and nobles; Petar Gojniković, Stefan Mutimirović, Pavle Branović. Mutimir maintained the communion with the Eastern Church (Constantinople) when Pope John VIII invited him to recognize the jurisdiction of the bishopric of Sirmium. The Serbs adopt the Old Slavonic liturgy instead of the Greek.^[18][22]

By the 870s, the Serbs were baptized and had established the Eparchy of Ras, on the order of Emperor Basil I.

Poland[edit]

The “Baptism of Poland” (Polish: Chrzest Polski) in 966, refers to the baptism of Mieszko I, the first ruler of a future united Polish state. His baptism was followed by the building of churches and the establishment of an ecclesiastical hierarchy. Mieszko saw baptism as a way of strengthening his hold on power, with the active support he could expect from the bishops, as well as a unifying force for the Polish people. Mieszko’s action proved highly successful because by the 13th century, Roman Catholicism had become the dominant religion in Poland.

Hungary[edit]

In the Middle Ages, the Kingdom of Hungary (which was larger than modern day Hungary) was Christianized initially by Greek monks sent from Constantinople to convert the pagan Hungarians. In 950, the tribal chief, Gyula II of Transylvania, visited Constantinople and was baptized. Gyula also had his officers and family baptized under the Orthodox confession.^[23] The conversion of the Hungarian people was not completed until the reign of Gyula’s grandson, King Stephen I of Hungary. Stephen was the son of Grand Prince Géza of Hungary and Sarolt, the daughter of Gyula II. His authority as leader of the Hungarian tribal federation was recognized with a crown from Pope Sylvester II. King Stephen converted the nomadic barbarian tribes of the Hungarians and induced them to sedentary culture. The conversion of Hungary is said to have been completed by the time of Stephen’s death in 1038.

Soon the Hungarian Kingdom counted with two archbishops and 8 bishops, a defined state structure with province governors that answered to the King. In the other hand, Saint Stephen opened the frontiers of his Kingdom in 1016 to the pilgrims that traveled by land to the Holy Land, and soon this route became extremely popular, being used later in the Crusades. Saint Stephen was the first Hungarian monarch that was elevated to the sanctity for his Christian characteristics and not because he suffered a martyr death.^[24]

Kievan Rus’[edit]

Between the 8th and the 13th century, the area of what now is European Russia, Belarus and Ukraine was settled by the Kievan Rus’. An attempt to Christianize them had already been made in the 9th century, with the Christianization of the Rus’ Khaganate. In the 10th century, around 980, the efforts were finally successful when Vladimir the Great was baptized at Chersonesos. To commemorate the event, Vladimir built the first stone church of Kievan Rus’, called the Church of the Tithes, where his body and the body of his new wife were to repose. Another church was built on top of the hill where pagan statues stood before.

Scandinavia[edit]

The Christianization of Scandinavia started in the 8th century with the arrival of missionaries in Denmark and it was at least nominally complete by the 12th century, although the Samis remained unconverted until the 18th century. In fact, although the Scandinavians became nominally Christian, it would take considerably longer for actual Christian beliefs to establish themselves among the people.^[25] The old indigenous traditions that had provided security and structure since time immemorial were challenged by ideas that were unfamiliar, such as original sin, the Immaculate Conception, the Trinity and so forth.^[25] Archaeological excavations of burial sites on the island of Lovön near modern-day Stockholm have shown that the actual Christianization of the people was very slow and took at least 150–200 years,^[26] and this was a very central location in the Swedish kingdom. Thirteenth-century runic inscriptions from the bustling merchant town of Bergen in Norway show little Christian influence, and one of them appeals to a Valkyrie.^[27] At this time, enough knowledge of Norse mythology remained to be preserved in sources such as the Eddas in Iceland.

Baltic[edit]

The Northern Crusades^[28] (or “Baltic Crusades”)^[29] were crusades undertaken by the Catholic kings of Denmark and Sweden, the German Livonian and Teutonic military orders, and their allies against the pagan peoples of Northern Europe around the southern and eastern shores of the Baltic Sea. Swedish and German campaigns against Russian Eastern Orthodox Christians are also sometimes considered part of the Northern Crusades.^[28][30] Some of these wars were called crusades during the Middle Ages, but others, including most of the Swedish ones, were first dubbed crusades by 19th-century romantic nationalist historians. Lithuania and Samogitia were ultimately Christianized from 1386 until 1417 by the initiative of the Grand Duke of Lithuania Jogaila and his cousin Vytautas.