Here is a map showing the dominant branch of religions across Europe and the middle east. In the Good old days of the Roman Empire these were all one religion. So how did these splits come about?
|Blue - Roman Catholic|
Purple - Protestant
Red - Eastern Orthodox
Light Green - Sunni Islam
Dark Green - Shi'i Islam
Like most things it had much more to do with politics than religious ideals.
If I was to blame one person it would be Constantine the Great as he organised the following
- The Council of Nicea (I will argue that by vilifying arianism in favour of trinitarianism, Islam became a seperate religion as it did not believe Jesus is God.).
- Founding Constantinople and which lead to a Greek vs Latin political divide which eventually led to the East-West Schism
|Constantine made some bad calls|
Christianity - Islam Split
Islam views itself as a more pure form of the same monotheist faith. Islams main issue with Christianity is due to Christianity's insistence on the divine nature of Jesus, which was enforced throughout the Roman Empire after the Arianists who didn't believe in this lost out to the Trinitarians at the Councile of Nicea. Muslim's see the doctrine of the trinity (God as father, son and holy ghost) as a corruption.
So arguably the seeds for the future split of Christianity and Islam occured at The First Council of Nicea in 325 AD Christian trinitarianism splitting from Arianism/Islam The Council enforced the doctrine of the Trinity across the Roman Empire. The reason for the Council was that Roman Emperor Constantine wanted to enforce one religious doctrine across the Empire, in order to ideologically unify the Empire's citizens. The main ideological issue is the nature of Jesus with Christians arguing Jesus is God (as part of Trinity) whereas Muslims (and Christian Arians) argue Jesus was just a Prophet.
|Arabs Conquer half of the Roman empire|
Sunni and Shi'i Split in 656 AD Sunni split from Shiite
Originated from Arab infighting over who was the rightful successor to Muhammad. The Sunni's beat the Shiites at the battle of The Camel which is why most of the Muslim world is Sunni.
|Arabs get into a fight over who's boss of the new Empire. Sunni's win. Persians|
hijack the Shiite cause to retain their territorial and political independence.
The Persian Empire began force converting it's land to Shia Islam, starting with Ismail I who began the Safavid dynasty and wanted an additional instrument for preventing the Ottoman Empire from easily conquering and assimilating it's territory. So this ideological split was introduced to unite peoples within the persian empire against the rest of the muslim world.
Christianisty split into Roman Catholic and Eastern Orthodox
Constantine split the running of the empire between the Greek run portions of the empire became managed seperartely to the Latin run portions. This had happened before, but he also set up a second centre of power to rival Rome, Constantinople. Rivaly between the Pope in Rome and the Patriach in Constantinople lead to the east west schism. The Eastern empire became eastern orthodox (and spread this to the slavs in Kievian Rus), while the successor states of the Western Roman Empire (notably the Carolingian Empire and it's successors France and the Holy Roman Empire) became Catholic.
|Constantine splits Roman Empire into East and West. This went on to become the|
Roman Catholic - Eastern Orthodox split. He also enforced the doctrine of the Trinity and outlawed
|East - West Schism leads to Roman Catholic - Eastern Orthodox divide. Basically|
boils down to The Pope of Rome and the Patriarch of Constantinople getting in a
Roman Catholic - Protestant Split
After the Romans lost the battle of Teutoburg Forest against German tribes, Rome never again tried to conquer and assimilate the German people. Protestantism spread almost exclusively among Germanic successor states (where Germanic languages are spoken).
|Language Map - There is a complete mapping of Protestants with Germanic speaking peoples. The only Germanic speaking people that Remained Catholic are those who were part of the Hapsburg Empire.|
This could have lead to a reform of the Catholic church without a split from the Church, so why did Germans, Scandanavians and English split from the Catholic Church? Because the Rulers of these regions wanted more power over the Church, and the pope's main enforcer, the Holy Roman Emperor no longer had the power to enforce unity.
This lack of power was ironically due to the Pope's own policies against the Holy Roman Emperor in previous centuries. The pope supported the Northern Italians and German Barons against the Emperor leading to defeat in Northern Italy and appeasement in Germany. In time this lead to further decentralisation of the empire which culminated the a religious 'civil war', the thirty years war that destroyed Germany and German religious unity. The Holy Roman Emperor could not enforce Catholicism on his subjects, it's princes chose there own flavors of Protestantism (Luther, Calvin, etc.)
|30 years war between protestants and Catholics in 17th century.|
Islam (Green) splits from Christianity (Blue, Red, Purple) with Mohammads teachings & Muslim Conquests
Sunni (Green) splits from Shia (dark green) with Ismail I of Persia
Roman Catholic splits from Eastern Orthodox with Pope Leo IX
Protestants (Purple) split with Catholics (Blue) after Martin Luther