How Christianity came to Medieval Europe

Nearly all the lands of Europe converted to Christianity during the Middle Ages. In this short guide, we take a look at how various lands adopted Christianity, including by means of missionary efforts, politics and warfare.

Early Christianity

Starting with the first followers of Jesus Christ, Christianity spread out into the Middle East and along the Mediterranean Sea to other parts of the Roman Empire. Although believers faced periodic Roman persecutions, the religion would grow, with some scholars suggesting that its idea about the resurrection of the dead and immortality of the spirit were appealing theological ideas, while others believe that the practical efforts of the church to help the poor was important in its increasing popularity.

Depiction ofJesus healing a bleeding woman, found in Roman catacombs, and dating from the first half of the fourth century – Wikimedia Commons


Armenia became the first country to establish Christianity as its state religion when, in the year 301, St. Gregory the Illuminator convinced Tiridates III, the king of Armenia, to convert to Christianity.

Constantine I

A 13th-century depiction of Pope Sylvester I and Emperor Constantine, found in the San Silvestro Chapel at Santi Quattro Coronati, Rome – Wikimedia Commons

Official persecution of Christianity had ended in the Roman Empire by the beginning of the fourth century, and support for the religion grew even among elites. It was under the reign of Constantine I (306-337) that Christianity became an official religion of the empire. Constantine himself had been introduced to the religion by his mother Helena, and according to Christian sources, he himself witnessed a miraculous cross in the sky before a battle. While Constantine himself did not become a Christian until he was on his deathbed, he supported the Church financially and oversaw its administration, even judging which religious beliefs were to be followed.



The fourth century also saw the rise of a new branch of Christianity, known as Arianism. Based on the teachings of a scholar named Arius, it advocated the position that Jesus Christ was created by God and not completely equal to him. While the mainstream Christian churches considered Arianism a heresy, it did find many followers, including a couple of Roman emperors. More importantly, some Germanic tribes accepted the Arian version of Christianity, including the Ostrogoths, who took over parts of Italy, the Visigoths, who seized control of the Iberian Peninsula, and the Vandals, who moved all the way into North Africa and ruled what is now Tunisia. The Vandal persecution of other Christians was one of the reasons why the Byzantine Empire conquered their territories in the years 533-34.

Rise of the Papacy

Even in the early centuries of Christianity, the Bishop of Rome made claims to be the head of the church, although it is unclear how much other parts of the Christian world accepted this claim or what it meant it practically. The Roman bishops, who were known as Popes, at times had considerable influence, but during parts of the early medieval period they were overseen and controlled by the Byzantine Empire. However, the Popes were also prominent in sending out missions to convert other parts of Western Europe. Gradually the Roman church broke off from their co-religionists in the Eastern Mediterranean – the main churches would be known as Roman Catholic and Orthodox.


Saint Patrick depicted in a stained glass window at the Church of St. Mary and St. Michael, New Ross, County Wexford, Ireland. Photo by Andreas F. Borchert / Wikimedia Commons

There was a Christian presence in Ireland by the year 400, and it is believed  that Saint Patrick, a Romano-British man who was once captured by Irish pirates and served as a slave, returned to Ireland and led efforts to convert the population. Through the work of him and others, a thriving Christian community was established in the fifth and sixth centuries, with Irish monasteries becoming centres of learning and many missionaries leaving Ireland to spread the Christian faith in the British Isles and continental Europe.


King Ethelbert baptized by Saint Augustine, as depicted in a 14th-century manuscript – Britiish Library MS Egerton MS 3028 fol. 55r

Efforts to bring Christianity to early medieval England were not as smooth, but during the seventh century Christian missionaries, sent from both Ireland and the Papacy, were able to convert various rulers. However, parts of the country would revert to paganism as the Vikings invaded and established their rule during the ninth and tenth centuries.


See also: Investigating ‘peasant conversion’ in Ireland and Anglo-Saxon England

Central Europe

The baptism of Clovis depicted in a 14th century manuscript – Bibliothèque nationale de France MS Français 2813, fol. 12 v

The baptism of Clovis I, ruler of the Franks, which took place on Christmas Day, 496, was an important milestone in the establishment of Christianity in continental Europe. Medieval historians have pointed out that the conversion of efforts of Christian missionaries was often a top-down process, in which they looked to convert their leaders of various peoples, with the hopes that the lower classes would gradually fall in line.

Carolingian Wars against the Saxons

The Carolingian Emperor Charlemagne led a series of campaigns against the Saxons, a Germanic tribe, in order to pressure them to convert to Christianity. This included the destruction of the Saxons’ holy site at Irminsul and the massacre of 4500 Saxon captives at Verden in 782. Three years later the Saxon leadership and peoples surrendered and accepted baptism.


While missionaries came to bring Christianity to parts of Scandinavia as early as the eighth century, it took a considerably long time before most of the region would abandon the Norse religion. Rulers such as Norway’s Olaf Tryggvason attempted to impose Christianity on his subjects, only to see them rebel and overthrow him. The Sami people, who live on the northern stretches of Scandinavia, did not accept Christianity until after the Middle Ages.



While Christian missionaries had come to Iceland in the tenth century and converted some people, others remained committed to their old religion. In the year 1000, during the Alþing – a general assembly of the Icelandic people – it was decided that the law speaker of the Alþing, Thorgeir Thorkelsson, would be given the role to arbitrate on which religion to choose for the people. After spending a day and a night thinking about the matter, Thorgeir decided that Christianity would become the official religion, while the Norse faith could still be practiced in private.

See also: How a volcanic eruption influenced Iceland’s Conversion to Christianity


During the ninth century, both the Papacy and the Byzantine church worked towards converting the Bulgarian peoples under their own jurisdiction. The Bulgarian ruler, Boris I (852–889) used this situation to court each side, looking for the best choice for his own strategic interests. Eventually, he was able to make a deal with the Byzantine Empire that allowed for the creation of a national Bulgarian church that was only loosely under the authority of the Patriarch of Constantinople. Even the Bulgarian language would serve as the official liturgy for this church.


The Christianization of Poland, as depicted by
Jan Matejko (1838–1893) – Wikimedia Commons

It was on 14 April 966 that Mieszko I, the first ruler of the Polish state, was baptized. According to early chronicles, much of the credit for this was to go his wife Dobrawa of Bohemia. However, historians believe that it was more likely that Mieszko accepted baptism in order to make an alliance with Dobrawa’s father, Boleslav I, Duke of Bohemia.

Kievan Rus’

Byzantine churchmen trying to convert the Rus, as depicted in the Madrid Skylitzes

By the ninth century the Byzantines were making efforts to Christianize the peoples of Eastern Europe in what is now Ukraine and Russia. While some people living in the region did convert, it was until the ruler of Kievan Rus’ Vladimir Sviatoslavich the Great (980-1015) that Christianity became the main religion. According to the Primary Chronicle, in the year 986 Vladimir met with representatives of several religions, including Jews and Muslims, to help him decide which religion to follow. He also sent envoys to neighbouring nations – those who came to Constantinople were very impressed with Hagia Sophia. Ultimately, Vladimir and his family were baptized and followed the Orthodox church.



After the Magyars invaded and conquered the Carpathian Basin at the end of the ninth century, efforts were made to convert them, with mild success. It was during the reign of King Stephen I (1000 or 1001–1038) that the monarchy undertook considerable actions to promote Christianity and remove their pagan religion. Stephen, who is regarded as the national saint of Hungary, made sure that churches were built and those who did not follow Christian practices were punished.


Tomb monument of Jadwiga of Anjou in the Wawel Cathedral. Photo by Romek79 / Wikimedia Commons

The last major holdouts to Christianity in Europe were peoples in the Baltic region – and during the twelfth to the fourteenth centuries crusades were undertaken to force these people to convert. The Teutonic Order was able to carve out a state for themselves in parts of the Baltic region, but the Grand Duchy of Lithuania was unconquered and becoming an important regional power. It was not until Grand Duke Jogaila (1377-1434) married the Polish Queen Jadwiga in 1386 that he was baptized as a Roman Catholic Christian (and becoming Władysław II Jagiełło). A year later he had the Lithuanian people baptized, although elements of the pagan faith survived past the Middle Ages.

See also: The Conversion of Lithuania 1387

Top Image: Clonmacnoise monastery in Ireland. Photo by Giuseppe Milo / Flickr