Summary: At one point the church of the East was as strong, or stronger than the Church of the West, but then it started a slow decline under persecution.
Once again, with the recent comments by President Obama and the violence of ISIS, the crusades are back in the news. And it is again popular for the average person to pontificate about the history of something that they have not actually spent any time studying. Philip Jenkins is trying to solve that, or at least the problem of a lack of information.
The main focus of the The Lost History of Christianity is of the 1000 year history of the church of Asia and Africa from approximately the 4th to the 14th century.
The image on the cover is a stylized map of Jerusalem in the middle with the three continents of Europe, Asia and Africa proceeding from it. At one point, there was far more balance in Christianity between the three continents than what is commonly understood today.
In the 4th century the great councils ruled on how to understand the divinity of Christ. The ‘winners’ of that fight we now call orthodox and the losers we call ‘heretics’. But everyone did not simply adopt the creed. Much (but not all) of the Eastern church continued to identify with what we now call the Monophysite heresy. These Christians are now called Oriental Orthodox (as opposed to Eastern Orthodox who did accept Nicaea) or Nestorians. They believe that Jesus Christ has one nature, not two, and was wholly divine. Modern scholars do not find as much difference between the two camps as might be assumed and so Jenkins wants to keep the understanding of them as Christian on the table.