1. Reformers of the Protestant Reformation
1.1. Protestant Reformation: the 16th century movement, which beginnings is generally attributed to Martin Luther, that challenged the political and religious authority of the established Catholic church.
1.1.1. Martin Luther
1.1.1.1. Debatably the most important figure in the Protestant Reformation, Martin Luther was a German Monk during the 16th century that challenged several Catholic doctrines in what is called his 95 Thesis, later being excommunicated.
1.1.1.1.1. Several countries, such as Sweden and Denmark, would sever ties to the Papacy and establish their own national churches based on Luther's theology. This effectively estranged these countries from the rest of Catholic Europe.
1.1.2. John Calvin
1.1.2.1. Originally a French lawyer, John Calvin became a prominent figure in the Reformation. His beliefs on free will (or a lack of) and predestination led to controversy with the Catholic Church, forcing him out of France and into modern day Switzerland.
1.1.2.1.1. Many of his followers in France, called "Huguenots" were suppressed and even killed for their beliefs in Europe.
2. The Early Church
2.1. Upon the death of the figure and founder of Christianity, Jesus's 11 apostles were sent out to preach to the people of the world and establish the church.
2.1.1. Though several communities and churches were established due to evangelization, 5 churches rose to prominence, collectively known as the Pentarchy.
2.1.1.1. Rome
2.1.1.1.1. The Church of Rome later became known as the Catholic Church, headed by the Pope.
2.1.1.2. Constantinople
2.1.1.2.1. Later called "New Rome" after the Great Schism of 1054.
2.1.1.3. Alexandria
2.1.1.3.1. The Church of Alexandria would break away from the larger charge body in the 5th century of doctrinal disputes, forming the Oriental Orthodox Church.
2.1.1.4. Antioch
2.1.1.5. Jerusalem
2.2. The Ecumenical Councils: Seven meetings of church hierarchs that convened to establish and define Christian doctrines. These councils would shape the beliefs and practices of Christianity forever.
2.2.1. The First Council: Stated that Jesus and God the Father were of one nature in a doctrine known as the Trinity.
2.2.1.1. Several minor factions would break from the church due to this belief, but very few lasted.
2.2.2. The Second Council: Further defined Jesus' relationship with God and added the Holy Spirit into the Trinity.
2.2.3. The Third Council: declared the Virgin Mary to be the "Mother of God"
2.2.3.1. This causes the first major split in the Church, with the Church of Modern-Day Syria leaving.
2.2.3.1.1. The Church remained relatively small, being dwarfed by the spread of Islam in the area.
2.2.4. The Fourth Council: Declared that Jesus has "two natures: one Divine and one Human."
2.2.4.1. The second major split occurs due to this definition, and many churches of Africa split from the larger body.
2.2.4.1.1. You would think such disagreements held little weight and made no sense, but these splits were integral to the development of the cultures in these respective areas.
2.2.5. The Fifth Council: Stated that just as Jesus suffered, so too did God.
2.2.5.1. Further split the Main Church from the Church of the East.
2.2.6. The Sixth Council: declared Jesus had two wills as well as two natures: a human one and a divine one.
2.2.7. The Seventh Council: Restored the use of sacred Christian art called Icons in the churches.
2.2.7.1. Many Protestants view the use of religious imagery to be a form of idolatry, leading to many conflicts.
3. The Great Schism of 1054
3.1. During this time, the Bishop of Rome, or the Pope, declared himself supreme over the entire church, a doctrine known as Papal Supremacy. This was counter to the belief that all bishops, or overseers of the church, were all equal. This all caused the West, allied with the Pope, and the East to split into two factions.
3.1.1. The Catholic Church
3.1.1.1. The largest Christian Church in the world, the Catholic Church is a communion of churches all under the jurisdiction of the Supreme Pontiff, or Pope.
3.1.1.1.1. The Catholic Church in European history had just as much temporal power as ecclesial, and often times monarchs were held accountable to the Pope.
3.1.2. The Orthodox Church
3.1.2.1. Second only to the Catholic Church in terms of adherents, the Orthodox Church resides mainly in Eastern areas such as Greece and Russia, making the church an integral part of their respective cultures.