What do we mean by “Crusader”?
From the time that the Muslims took over Palestine around 630 AD until 1948, Palestine was controlled by various occupiers. Turks, Egyptians, the British, and many Muslim caliphates. But there was a period of time right in the middle where Palestine was controlled by the Catholic Church.
In 1009 there was a Muslim Caliph, Al-Hakim, who tore down the Church of the Holy Sepulcher, which is why the original tomb of Jesus does not exist today. It did prior to this time.
This act was the trigger that started a military campaign by the Roman Catholic Church to take back the Palestine from the Muslim occupiers. Starting in 1095 AD, and for the next 200 years there was a constant struggle to control the Holy Land. There were six or seven major crusades launched by the Catholic Church, and numerous minor ones. Thousands of sword-swinging Catholics marched on the middle east.
The reason for the Crusades sounds like one of religious fervor and devotion, but there were probably other reasons – politics, land, economics, building empires, defeating other Christian rivals. Whatever it was, the Catholics and Muslims were at war with each other, and in one case it was the Catholics versus Orthodox Christians.
During the Crusades the Catholic popes became military commanders, and to protect or advance their interests, these popes initiated wars against Muslims, against pagans, and even against non-Catholics. This means that in the 12th century, the Catholic Church was doing what the Muslims did in the 7th century. They started evangelizing with the sword. The way they succeeded in converting people to Catholicism was by conquering them, killing enough of them where an entire societal conversion to Catholicism could be easily mandated.
The Crusaders were not necessarily righteous people. They pillaged lands that they traveled through. They murdered thousands of Jews and Orthodox Christians, and even persecuted other Catholics.
In fact, the fourth Crusade wasn’t aimed at attacking Islam or the Holy Land at all, but rather attacking the Christian Orthodox Byzantine Empire in Constantinople, which had just broken away from the Catholic church in the eleventh century. 800 years later, in 2004 there was a formal reconciliation between the Catholic and Orthodox churches over the atrocities of this fourth Crusade.
The Crusades were wrong. They were an example of religious power gone bad. It was a case where the Christians, who were persecuted at the beginning of the first millennium, became the persecutors starting at the beginning of the second millennium.
When the Crusaders came here to Palestine, they started building, and many of the places we visit nowadays were built by them, such as the current church of the Holy Sepulcher, the current Upper Room, the synagogue of Jesus in Nazareth, the Church of Saint Anne, and the Damascus Gate – all crusader constructs.
Israel is a big melting pot of archeological history, and it’s easy to get it all confused. Of all the places we see in the modern state of Israel, some of them date back to the Crusader days of eight or 900 years ago. Some ruins go back to the time after the Crusader period, when the country was occupied by Arab powers. Some ruins go farther back to the time of the Persian conquest before the Crusades. Some ruins go back to the Byzantine days, when Christianity was booming in Palestine. Some ruins go back even farther to the days of the emperor Hadrian in 135 AD, when he modified the city, and renamed it Aelia Capitolina. Some ruins go back to the Roman days before 70 AD. Some ruins are specifically Herodian, which means they were built by Herod the Great. And some ruins go back even farther than that, to the Maccabean era, when Palestine was self-ruled before the Romans took over.