Philip Jenkins’ “The Lost History of Christianity” is about the largely extinct Christian churches (principally the Jacobites and Nestorians) that ranged from Africa to China, and are regarded now by the surviving small-o orthodox as heretical sects that may even deserve their extinction due to their welcoming of conquering Muslims. That’s perhaps a caricature of the view Jenkins is arguing against, as he aims to show there was a genuine loss of something distinct, accomplished and important in an historical sense. The interesting bit to me (and for the most part, I don’t find the subject interesting) is how the extinction came about. One might expect it happened almost immediately after the Arab conquests, but that appears to only have been the case in north Africa (Egypt not included, the Coptic church has proved to be surprisingly durable). Alternatively there could have been a long gradual process of attrition as Christians converted to avoid things like the jizya and other demerits of dhimmitude. But instead Jenkins argues that it largely occurred in a couple centuries around the year 1300. There a number of factors that caused everything to fall apart. There were prolonged wars of Turkish conquest (in contrast to the quick Arab absorbtion of weakened Byzantine and Persian territories, largely leaving literate locals in charge and unmolested), a series of Crusades that made Muslim vs Christian conflict more salient, and eastern Christians pinning their hopes on the initially relatively Christian-favoring (and practically genocidal) Mongols only for their imagined saviors to themselves convert to Islam. But additionally Jenkins finds that things were going from bad to worse in Europe as well, with Jews being expelled from England & France (the latter of which had a crusade against the heretical Cathars) and the witch-hunts being launched. For the material determinists out there he offers the cooling of the planet, with ensuing crop failures and epidemic outbreaks as the reason for everything going wrong around the world. So perhaps global warming will help lead to more world peace.

Some quotes from that section of the first chapter:
“Even today, jihadi extremists look back to the hard-line Muslim scholars of this very era as their role models in challenging the infidel world.”*
“Anyone who believes that boundless aggression and ruthless tyranny over minorities are built into the DNA of Islam needs to explain the quite benevolent nature of Muslim rule during its first six centuries; but advocates of Islamic tolerance must work just as hard to account for the later years of the religion’s historical experience.
So extensive, indeed, were persecutions and reductions of minority groups, from the Middle Ages through the twentieth century, that it is astonishing how little they have registered in popular consciousness, or how readily the myth of Muslim tolerance has been accepted. One factor distorting memory has been the total oblivion into which the non-European Christian communities have fallen, and the assumption that the familiar realities of the present day must always have existed.”
*I would have assumed that Muhammad himself and the rightly-guided caliphs are the only ones your genuine fundamentalist should approve of. Islam totally sold out in its later years.

I’d also like to include this quote on the myth of suppressed gnostic Christianity.
“In recent years, accounts of the early church claim that scriptures and gospels were very numerous, until the mainstream Christian church suppressed most of them in the fourth century. This alleged purge followed the Christian conversion of the emperor Constantine, at a time when the church supposedly wanted to ally with the empire in the interests of promoting order, orthodoxy, and ecclesiastical authority. According to modern legend, the suppressed works included many heterodox accounts of Jesus, which were suspect because of their mystical or even feminist leanings.
The problem with all this is that the Eastern churches had a long familiarity with the rival scriptures, but rejected them because they knew they were late and tendentious. […] The deep conservatism of these churches, so far removed from papal or imperial control, makes nonsense of claims that the church bureaucracy allied with empire to suppress unpleasant truths about Christian origins.”