Why does Christianity and orthodox split?

Answer 1

Eastern Orthodox Christianity is Christian!!

If you are asking why the Roman Catholics left the Orthodox Church, the answer is very complex.

The Roman Empire was rather large. Over its first 300 years, the Church spread to many places, among them were Ephesus, Smyrna, Pergamos, Thyatira, Sardis, Philadelphia, Laodicea, Colossus, Galatia, Rome, Egypt, even India and Ethiopia. Meanwhile, the Roman Empire was so large, it ended up with 2 capitals: Rome in the west and Constantinople (as it came to be called) in the east.

Constantine was the emperor in the East at the time Christianity was accepted as the official religion of the Empire. Because there had come to be controversies about the beliefs of the Church, Emperor Constantine called a great council held in Nicaea in 325ad. This council repudiated the heresies of Arianism, developed the original Nicene Creed (still accepted in the Orthodox Churches), set the date for Easter (still observed in the Orthodox Churches), accepted that Jesus Christ is of one substance with the Father. Other theologic questions were settled at the following 6 Ecumenical Councils [First Council of Constantinople (381), Council of Ephesus (431), Council of Chalcedon (451), Second Council of Constantinople (553), Third Council of Constantinople (680-681), Second Council of Nicaea (787)].

The Roman Empire continued to expand, particularly into Western Europe, bringing Christianity with it. In the 7th century, beginning in Spain, a new phrase was inserted into the Nicene Creed. The Creed originally stated that the Holy Spirit "proceedeth from the Father." The new phrase stated that the Holy Spirit "proceedeth from the Father and the Son" (and the Son = filioque). The Eastern Church rejected this phrase because it contradicted the meaning of the original Nicene Creed. This became a great disagreement between the Bishop of Rome and the Bishop of Constantinople. This, along with the rejection of the Bishop of Rome's contention that he was the "head" of the Church (as opposed to being the "first among equals" with the other bishops), eventually led to the Great Schism wherein the Orthodox East and Catholic West "excommunicated" each other.

The Eastern Orthodox Churches (there are many) all adhere to the theology of the New Testament and to the theological explanations of the Seven Ecumenical Councils.

All of the Protestant Churches began splitting away from the Roman Catholic Church in the 16th century, first, after Martin Luther, and following that continued splitting off not only from the Roman Church but from other groups that had split away. Most of the Protestant Churches are no more than 250 years old.

So, to make this very long story shorter, the Orthodox Church was the original Christian Church.

See below diagram that makes this more clear: (related links)