How did the Great Schism affect the spread of Christianity in the East?

Catholic Answer You are asking about the Schism of the East, NOT the Great Schism.

The Great Schism, otherwise known as the Western Schism is not to be confused with the Schism of the East.

The Schism of the East was when the Eastern Church broke into two factions, half staying with Rome, and half formed what is now called the Orthodox Church.

What is called the Great Schism in the Catholic Church was the Western Schism, which, even more confusing, was not really a schism in the sense that the Schism of the East was, but a time when the Church had more than one claimant to the Papal Throne, finally resulted in three, one pope and two antipopes.

The Schism of the East split each of the eastern Rites of the Church in half, with half remaining with Rome, and half becoming what is now known as the Orthodox Church.