Philip Jenkins' Lost History of Christianity tells the story of great Christian movements that happened east of Jerusalem. What was great about these movements? Why did they not survive? So what? What difference should this make for us today?
It is encouraging to learn that as the gospel spread with Christ's disciples and was widely accepted far beyond Europe. The fact that Christianity once flourished under the Western Church, the Orthodox Church, and the Eastern Church of Africa and Asia dispels the common myth that Christianity is strictly “western” when in reality it is universal. Also to know that Christ is actually returning to Asia and Africa and not arriving can act as a bridge for evangelism.
The death of the Eastern Church in Africa and Asia shows that Geo-political and religious factors contribute to the spiritual warfare surrounding a faiths survival. Persecution from an intolerant government led to dwindled church numbers as believers fled likely to be absorbed by existing churches in those regions instead of starting new ones. The church and state alliance prior to Arab control likely produced many “name-only-Christians” whose faith was shallow and susceptible to conversion. However, realizing that throngs of Christians simply identified with Christ through their sufferings for a century, living out of their persecutor's reach (Maronites in Lebenon) or worshiping underground (crypto-Christians) speaks loudly to the truth of Christ.
Forgetting the history of the Eastern Church is dangerous since the Western Church is not immune to those destructive Geo-political and religious threats. Persecution of Christians in the western world could just as easily send believers abroad leaving their churches behind. The rise of fundamentalist atheism and syncretistic pluralism has already converted “Cultural Christians.”
The Eastern Church's history also discredits a “Darwinian Theology,” where only true beliefs survive. Also, their monophysite view raises the question of how much technical knowledge of Christ is needed to be saved? If the salvation of the thief on the cross is any example, the church ought to approach disagreements with gentleness and respect, letting scripture teach and rebuke.