How Orthodox Church came into existence.

Most of us would have difficulty understanding God's word if today it were available only in ancient forms of languages - Hebrew, Greek and Latin. In the 9th century C. E., Methodius and Cyril, Thessalonian missionaries acting on behalf of the Eastern church in Byzantium promoted the use of slavic as church language. Their goal was to enable the Slavic peoples of Eastern Europe, who understood neither Greek nor Latin, to learn about God in their language.
These missionaries, however, met with fierce opposition from German priests, who sought to impose Latin as a defense against the expanding influence of Byzantine Christianity. Clearly, politics were more important to them than people's religious education. Increasingly tensions between the Western and Eastern branches of Christendom led to the division between Roman Catholicism and Eastern Orthodoxy in 1054.