In this century, Christianity faced another religious doctrine that had formed an army which, since the previous century, had grown at a frightening pace: Islam. Muslims organized themselves very quickly across the world. They spread throughout the Arabian Peninsula and took North Africa very rapidly. The Christian Roman Empire then experienced a process of retreat because of the growth of this new force that imposed itself.

From this century on, Christianity would experience a second change in its profile. In its earliest times it was doctrinal and religious, but it ended up becoming more formal and more connected to aspects of power, which was its first change. From this point in history, it became a warrior doctrine. When we speak of Christianity in this century, we are speaking of soldiers, warriors, and men carrying swords in their hands, because they had motivation to fight since they were dealing with an enemy.

Christianity then entered a new phase, a second transformation: the phase of battles, of armies that, in the name of Jesus, drew their swords to kill opponents in the name of faith. This is the tone of the eighth century, and it would spread for several more centuries. From then on, there was a clash of cultures and a clash of ideologies, with both sides wanting to prevail.

A large part of the expansion of Islam happened in the previous century, at the time of its birth. In this eighth century, the Christian Roman Empire was extremely afraid because it was being devoured by the Muslim Empire in a very significant way, since along with military force came religious culture. It was a religious army coming to convert the masses of the Roman Empire.

When, in 638, the caliph Umar took Jerusalem, he ordered a mosque to be built, today known as the Mosque of Umar. Later he ordered the Dome of the Rock to be built so that the foundations of Islam would be established there.

In this century, a great caliph named Tariq ibn Ziyad crossed the Strait of Gibraltar and, in the year 711, took the Iberian Peninsula, that is, Portugal and Spain, which came under Muslim control. They also tried to expand into the rest of Europe. However, when they attempted to enter France, they faced the Carolingian dynasty, from the name Charles, led by Charles Martel.

A curiosity: mountain in Arabic is jabal, and when the army of Tariq ibn Ziyad reached Spain through a narrow passage, that mountain became known as Mount Tariq, because it was there that Tariq crossed to begin the domination of the Iberian Peninsula. The strait became known as Jabal Tariq, today called Gibraltar.

After Charles Martel, his son entered history as Pepin the Short because his reign was very brief. After him came his grandson Charlemagne. In 732, Muslims tried to capture two French cities, Tours and Poitiers. But for the first time after conquering the Iberian Peninsula, they were defeated by Charles Martel.

In Poitiers and in Tours, two battles took place. Charles Martel, who at that time was the ruler of the Franks, won these battles, defeated the caliph and his warriors, and expelled them from France. If it were not for him and his Carolingian dynasty, perhaps today all of Europe would be Muslim. For the first time, Christians took up arms and became warriors because they needed to defend their faith, but not like the ancient apologists, who defended faith only with arguments. At that moment Christians also became warriors to defend their territories.

Charles Martel achieved significant victories that gave him enormous power. He was seen by the population almost like an idol, an extraordinary winner. However, he was not truly a king, yet he gained great popularity even without throne and crown.

Two very significant events occurred during the reign of Pepin, his son. Pope Zachary went to France to anoint him king. Thus an alliance was formed between temporal power and religious power, between the State and Religion. Pepin granted some lands to Pope Stephen II, successor of Pope Zachary. With this donation of land began what the Church calls the Papal State. The Church then began to have land and property.

Even more relevant than Charles Martel and Pepin was Pepin’s son, Charlemagne. He had enormous importance in this period because he unified the Western Roman Empire, which was completely fragmented after its fall.

Charlemagne reigned until 843. In the year 800, still within this century, more precisely on December 25, Pope Leo III went to France and crowned him Emperor. Thus the Holy Franco Germanic Empire was created, similar to the Roman Empire but with a different name and territory, now covering all of Europe except Portugal and Spain. Europe, which had already freed itself from emperors, had one again. But this one was different, because an imperial power was now needed to defend against Muslim invasions.

Charlemagne promoted the Carolingian Renaissance, meaning a period of investment in the arts, in beautifying cities, and in an even stronger union of the State with the Church, which from then on walked together. The Byzantine Empire still existed, so a strong emperor in the West was needed to stand against his counterpart. Power struggles like these are common throughout history.

Charlemagne’s period as Emperor was one of peace with Islam. Jerusalem was entirely in Muslim hands, and yet Christians could make pilgrimages to the holy city. They could come and go and there was no obstacle from Islam and no conflict, because Charlemagne respected the administrative and political control of Jerusalem in Muslim hands. He did not call an army to retake Jerusalem, so there was peace in that period.

A very important caliph was then elevated, one of the wisest caliphs Islam ever had: Harun al Rashid. His wisdom was remarkable, and when he took power, he said: “I will make our empire the wisest and most powerful the Earth has ever known.”

He discovered that Christians were destroying knowledge in their regions. Ancient scrolls in Alexandria were being burned. Texts by scholars, philosophers, great mathematicians and geometers were being destroyed or forgotten. Christianity at that time held a very rigid position regarding science.

Harun al Rashid then sent a team of Arabs from Baghdad into the Christian world to seize any scrolls they could find. They did so and took what they found back to Baghdad. However, the scrolls were written in Latin, Greek, or Hebrew, so they first had to be translated into Arabic. Then he ordered the construction of a great library to store all that captured wisdom. He revived the idea of the Library of Alexandria, a single place where all knowledge would be concentrated.

He also built an institution called Bayt al Hikmah, the House of Wisdom, where the knowledge of humanity was gathered. In this way, Islam rose in knowledge across many sciences. Great scholars, called polymaths, gathered there so that, by order of the caliph, knowledge would be made accessible to the entire Arab nation. Thus a gap began to grow between Islam and the Christian world, which became more backward and more ignorant, while Islam developed.

They studied ballistics, which much later Galileo used to calculate cannon angles. They studied optics and astronomy. They created a series of major inventions. They discovered anesthetics extracted from poppy leaves and many things Christians did not know. Many kinds of knowledge were obtained in the House of Wisdom.

This wise caliph was a close friend of Charlemagne. However, they never met and frequently exchanged gifts. When pilgrims passed through the caliph’s lands, Charlemagne sent him a present, and in return the caliph sent another. Charlemagne’s gifts were modest and not very luxurious. The caliph, however, gave ingenious objects, such as the time he gave Charlemagne a water clock, considered one of the most sophisticated inventions of that period.

So the House of Wisdom marked the peak of Islam in this century. It was during the Abbasid caliphate that Baghdad, in ancient Mesopotamia, was built and the House of Wisdom was established there. However, after an early golden period, it declined after the Crusades because of the intolerance that followed from both sides.

Harun al Rashid and Charlemagne concluded that if they kept a state of war they would not prosper, and they decided to live together with mutual respect.

In this century, deep divergences began to arise between Byzantine and Catholic beliefs. Jews believe in God, monotheism, but not in images, according to the second commandment. Christians, coming from a Jewish origin, held the same position. However, after the Roman Empire became Christian in the fourth century, Christians began to absorb Roman customs, including practices connected to the worship of gods. There was a partial assimilation of Roman culture regarding worship, because they began to idolize human figures, such as important leaders, through images carved in wood.

In the Byzantine Empire, the movement of the iconoclasts arose. The word clast means to break, to destroy. According to its defenders, the use of images in worship was staining Christianity. This debate about whether Christians should venerate saints or not led to the Second Council of Nicaea in 787.

At this council it was decided that neither iconodulia, the worship of images, nor iconoclasm, opposition to images, would be fully endorsed. It was defined that worship should be directed only to God, but that a form of gratitude and veneration toward the saints of the Church could be expressed.

This was the first major objection regarding devotion to saints. Centuries later, a schism would occur among Christians, separating those recognized as Orthodox, without the cult of images, and Catholics, who use images in devotion.

Three important facts stand out in this century: Muslim expansion, the Carolingian Empire, and iconoclasm. But the most important point was the peace that existed between Catholics and Muslims.