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The Byzantine Empire versus the Persians

Although the Western Roman Empire ended in A.D. 476, the Byzantine Empire (formerly known as the Eastern Roman Empire) survived in the east. (To see the dividing line between the Western and Eastern Roman Empires, see this Map.) In A.D. 572, the Persians made war with the Byzantine Empire. In 614, the Persians attacked the city of Jerusalem, killed 60,000 people, and carried off the relics of the Holy Cross that St. Helena found. By 622, the Persians had won Syria, Turkey, Palestine, and Egypt. The Christian Byzantine Emperor Heraclius I, who reigned from A.D. 610 to 641, organized a new army and won against the Persians in a decisive battle, known as the Battle of Nineveh (A.D. 627). In 629, he recovered the relics of the Holy Cross and brought them back to Jerusalem, a significant event that is still celebrated by the Church every year on September 14. All the countries conquered by the Persians were also returned to the Byzantine Empire. For this victory, he was honored as a savior of Christian civilization.

Battle Between Heraclius I and the Persians

Painting by Piero della Francesca (d. 1492)

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The Rise of Islam

In Arabia, the seventh century saw the rise of the religion of Islam. Mohammed (A.D. 570–633), the founder of Islam, did not preach religion until he was forty. His famous book, the Koran (or Quran), contains a mixture of tales and sayings taken from the Holy Scriptures and pagan folklore. Mohammed believed in Allah, the one God (Quran 112:1), of whom he claimed to be a messenger and prophet (Quran 33:40). He did not believe in the Trinity nor the divinity of Jesus, claiming that Jesus was no more than a prophet or a messenger of God (Quran 5:73–75). For references to the Koran or Quran, see (Mohammed did not write the Koran himself because he could neither read nor write. His teachings were initially memorized and then recorded later in writing by his followers.)

Mohammed gained many followers when he began to preach, but he also made many enemies among the polytheistic and idolatrous people of Mecca (in Arabia). To avoid the persecution of his enemies, he fled to the city of Medina (in A.D. 622) where his teachings were accepted. There he gathered more followers and began to wage war against those who wouldn’t accept his teachings, calling them “infidels” or “unbelievers.” His enemies were not merely the pagans but also Jews and Christians (Quran 5:51; 9:30). To Mohammed, the Christians were also unbelievers because they accepted the Trinity (Quran 5:73). He told his followers that it was their duty to engage in a “holy war” (Jihad) against the unbelievers, promising salvation for those who die for Allah (Quran 9:111; 4:74). According to the Koran, this holy war was not meant to be just a war of words or an intellectual debate with people of other religions. It was meant to be an actual war (Quran 5:33) and included inflicting terror or terrorism against the enemies (Quran 8:12). Of course, not all present-day Islamists follow this extreme prescription of the Koran. They felt that the Jihad may also be carried out by other forms of warfare, including spiritual, psychological, social, and intellectual, and does not have to involve bloodshed.

In A.D. 630, Mohammed returned to Mecca and conquered it. Shortly thereafter, the religion of Islam spread throughout all of Arabia. Mohammed died in A.D. 633, but Mohammed did not name a successor before he died, which explains why there are now two major divisions of Muslims: the Sunnis and the Shiites.


After Mohammed’s death, his followers carried out their holy war outside of Arabia. By the early part of the eighth century, they had conquered Palestine (including the city of Jerusalem), Syria, Egypt, Persia, much of Northern Africa, and a greater part of Spain. The small islands in the Mediterranean, namely, Corsica, Sardinia, Sicily, Crete, Rhodes, and Cyprus, were also subdued. In all those places conquered by the Muslims, Christianity was destroyed and replaced by Islam. However, by using the great libraries in Syria and Egypt, the Muslims also acquired great skills in trade, the sciences, art, and philosophy.The Christian theologians of the Middle Ages derived a better understanding of the philosophy of Aristotle from the works of Muslim philosophers.

At that time, the followers of Mohammed were called by various names. In Arabia, they were known as the Arabs. In Spain, they were called Moors; in France, they were referred to as the Saracens. Today, they are simply referred to as “Muslims.”


On account of their past conquests, it seemed like the Muslims would dominate all of Europe and all of Christendom. But by divine providence, things changed. In the east, the Byzantines defeated the Muslims at Constantinople (A.D. 718). In the west, the Franks, under the leadership of Charles Martel (aka “the Hammer”), also stopped their advance in the Battle of Tours-Poitiers (A.D. 732), which left three hundred thousand Saracens dead on the field. This effectively arrested the further expansion of Islam in Europe. However, the Muslims continued to be a threat in Europe for centuries. In Spain, the stranglehold of the country by the Moors would not end until 1492.

The Monothelite Heresy

At the same time that the errors of Islam were spreading throughout Europe, the heresy of monothelitism was also gaining ground in the Church of Constantinople. Sergius, their patriarch, supported the idea that there was only one will in Christ: the divine will. Therefore, like the Monophysites, he denied the full humanity of Christ and affirmed that Christ only had a divine nature. He was opposed to this issue by the learned St. Sophronius the Wise (A.D. 560–638), Patriarch of Jerusalem, who is also presently regarded as one of the Fathers of the Church. Pope Honorius I (A.D. 625–638) was consulted on this matter, but he did not resolve it. However, in A.D. 680, the Third Council of Constantinople upheld the teachings of St. Sophronius and condemned the Monothelite heresy. See the List of Ecumenical Councils.

The Partial Christianization of Germany

The monasteries in England produced many missionaries. One of the Anglo-Saxon monks, St. Boniface (A.D. 675–754), originally named Winfrid, went to work in Frisia (now part of the Netherlands). However, in A.D. 719, Pope Gregory II commissioned him as a missionary bishop to Germany. He obeyed and worked tirelessly to convert many territories in Germany. Protected by the Frankish commander, Charles Martel, he evangelized Hesse, Thuringia, and Bavaria but failed to convert the Saxons, who continued to worship their idols. The complete conversion of Saxony (Northwest Germany) was not accomplished until the reign of Charlemagne. St. Boniface and his companions were martyred in A.D. 754 when they returned to Frisia, but on account of his outstanding work in Germany, he is known today as the Apostle of Germany.

St. Boniface Leaves England

From a prayer card featuring the painting of Johann Hess

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Rome against the Lombards

In the sixth and seventh centuries, the Popes paid a yearly tribute to the Lombards—the barbarians who controlled northern Italy—to keep them from invading Rome. Pope Gregory I (aka Pope Gregory the Great) had to make this treaty with the Lombards because he could not get any assistance from the Byzantine Emperor. This lack of cooperation between the Byzantine Emperor and the papacy continued during the pontificates of Pope Gregory II and Pope Gregory III. Occasioned by the heresy of iconoclasm, the strained relationship between the papacy and the Byzantine Empire even worsened. Iconoclasm was the heresy that taught that it was sinful to venerate the images of our Lord, the Virgin Mary, and the saints. In support of this heresy, the Byzantine Emperor, Leo III the Isaurian, issued an edict in A.D. 726, ordering all religious images to be destroyed throughout the Empire. Pope Gregory II opposed this edict. The emperor sent an army against Rome, but the pope appealed to the Lombards for help. The Lombards repelled the emperor’s army.  St. John Damascene (A.D. 676-750), a Father and Doctor of the Church, was the champion of the Church in its defense against this heresy, which was eventually condemned by the Second Council of Nicaea in A.D. 787.

In A.D. 754, the Lombards decided to attack Rome and force the then Pope Stephen II to leave the Eternal City. This time, the pope turned to the French King Pepin (the Short), son of the Frankish military leader, Charles Martel, for assistance. King Pepin successfully drove the Lombards out of Rome and even recovered many of the territories conquered by the Lombards. Then, by a solemn act, King Pepin donated these territories, which included Rome, Ravenna, Bologna, Ferrara, and several other towns, back to the Pope. These recovered territories came to be known as the Papal States.

In A.D. 774, the Lombards tried again to attack Rome. This time, Pope Adrian I asked Charles the Great—better known as Charlemagne (A.D. 742–814), the son of King Pepin—for help. Charlemagne came to the rescue, defeated the Lombards, and added more territories to the Papal States. The Church owned extensive lands even during the fourth century. These lands were gifts to the pope and were known as the Patrimony of St. Peter. But, although the Church owned these properties, the pope did not rule over them.  However, the Papal States donated by King Pepin and later by Charlemagne were different. The Pope ruled over these states like a king.

Pope Adrian I Asking Charlemagne for Help

Hand-colored print by Antoine Verard

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Since that time, the popes, while acting as Supreme Pontiff for the Universal Church, also governed the Papal States as civil rulers. To govern like a temporal king was neither a necessary nor the most important function of the pope, but being able to govern the Church as a sovereign also gave the pope a certain advantage. He could make religious decisions without undue pressure or opposition from any king. However, this kind of union of Church and State also had its drawbacks. As a civil ruler, the pope had to be involved with secular affairs and maintain peace with other kingdoms or civil powers in Italy.

But this ended in 1870. What happened was that King Victor Emmanuel of Sardinia, who wanted to have a united Italy, forced the Austrians to withdraw from Northern Italy and then invaded the Papal States, including Rome. The pope lost his temporal power to govern the Papal States. However, the then Pope Pius IX refused to leave the Vatican and, by his choice, became a prisoner in the Vatican. Sixty years later, under the pontificate of Pope Pius XI, the hostility between the Italian government and the pope was resolved by the Lateran Treaty of 1929, which recognized the Vatican as an independent state.

Charlemagne and the Conversion of Saxony (Northwest Germany)

Charlemagne did not merely defeat the Lombards in Italy, but he also invaded the Saxons in Northwestern Germany. He wanted the Franks and the Saxons to have peace, and he thought that the best way to do this was to convert the pagan Saxons to Christianity. He used his superior military power to quell all Saxon rebellions (A.D. 772–804), but his treatment of the Saxons was severe. Although the Saxons converted to Catholicism after their defeat, it became obvious that true conversion could only be done by faith and not by force. A forced conversion often resulted in an insincere conversion and disloyalty. However, many Saxons at that time also converted, not out of fear of punishment or death but through the painstaking work of Benedictine missionaries who illumined and guided their faith.

Charlemagne, Patron of Learning

Charlemagne was a great warrior, but he was also noted for bringing education to the people. He invited the best scholars in Europe to his palace in Aachen and placed his distinguished friend and adviser, Alcuin of York (A.D. 735–804), in charge of the palace school. Alcuin was a great teacher. He spoke several languages, including Latin, Greek, and Hebrew. He was not only a master of philosophy and theology but also history and mathematics. Students from all over Europe came to listen to his lectures.

Charlemagne strived to make education accessible to everyone. By the advice of Alcuin, he ordered the establishment of a primary school in every parish, village, and town. Every church must have a school, which was to be under the charge of the parish priest. The priests were to give free education to everyone, and the priests themselves were required to have a certain minimum level of education. The parochial schools that are seen today have their roots in the dream of Charlemagne to provide free education for all.

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