The Holy Mountain of the title is Mount Athos in Greece, where the author visits a monastery to see the original manuscript of The Spiritual Meadow, a record of the wisdom and travels across the Byzantine Empire of John Moschos, a monk who lived in the 6th and 7th centuries. Dalrymple's journey, inspired by Moschos, takes him around modern Turkey, Syria, Lebanon, Israel, the occupied Palestinian territories, and Egypt. Throughout, he brings not only the present but also the past world of Byzantium vividly to life, introducing us to a series of extraordinary characters who he portrays with sympathy and humour.

While Dalrymple has a masterfully comic touch, this book is far more than a collection of travel anecdotes. Its main theme is the decline of Christianity since the days of John Moschos, when the greatest threat seemed to come from the Persian Empire. Today, the threats are different. In several cities, the author meets with communities which seem to be in their last days: the Greeks in Istanbul, the Greeks – and Jews – of Alexandria, the Armenians of Jerusalem. In south-east Turkey we meet Lucine, the last Armenian in Diyarbakir: an old woman, her wits astray, her fine church going to ruin. Where Christians have already been driven out, past traces of their existence are also being deliberately destroyed or obscured: in Turkey, cathedrals are converted to mosques and churches are dynamited as the genocide of Armenians continues to be officially denied; in Israel, prominence is given to any site indicating a past Jewish presence while significant Christian archaeological sites are reburied or not properly preserved.

Though he writes from a Christian perspective, the author is not partisan. Contentious claims are investigated sceptically. When it comes to personal stories, he is just as anxious to record the precious memories of the disappearing Jews of Alexandria as those of its dwindling Greek population. He does not shrink from telling us about the Maronite Christians in Lebanon who estimate their supremacist leader's holiness by his attendence at daily mass – while disregarding his propensity to murder men, women and children. The atrocities of the Phalange stand in contrast with the generosity of Muslims towards Christian Palestinian refugees – illustrated by the heartbreaking story of Samira Daou's family – just as the traditional Muslim tolerance of other faiths, including Judaism, compares favourably with a history of crusades, inquisitions and gas chambers.

Irresistible stories are sprinkled though the book. Some are told by people the author meets: the tale of the fifty gold pounds and the brigand Ali ibn Mohammed in the Syria of the 1920's; the assassination-by-installments of Abu Zeid, the reviled Palestinian mayor with more lives than Rasputin. Others are the author's own: hair-raising encounters with secret police; an uproariously funny trip with an Egyptian taxi driver. Eccentric characters and their beliefs are sketched deftly, from the Byzantine-era dendrites who “took literally Christ's instruction to imitate the birds of the air, living in trees and building little nests” to the modern Orthodox monks who would be no less scandalized to discover that Dalrymple was Catholic than to hear him confess to being syphilitic. The humour is gentle rather than mocking; there is a sensitivity to the numinous world of the present-day faithful and a respectful appreciation that “what has most moved past generations can today sometimes be only tentatively glimpsed with the eye of faith, while remaining quite inexplicable and absurd when seen under the harsh distorting microscope of Western rationality.”

Lively personal accounts are complemented by careful research: Dalrymple not only cites the authorities, he meets them. His knowledge of the history of culture, art and beliefs allows him to set his experiences in context and to identify intriguing connections spanning centuries, countries, and religions – whether linking the beehive huts of Mar Saba in the West Bank with those of Skellig Michael at Europe's western extremity, or the architecture and traditions preserved by Syriac Christian communities he visits with those of modern Islam. On all these subjects, Dalrymple writes with such flair that it is hard to avoid sharing in his enthusiasm: we are carried along by his description of the “fizz of dissolving philosophies” in ancient Alexandria just as surely as we are on his journey through the crackling war zone of eastern Turkey.

Among the most interesting passages in this book are Dalrymple's observations on Islam. A religion which was just beginning to dawn in the days of John Moschos (Mohammed was a contemporary), it was at first seen as a heretical version of Christianity – one of many which included, for example, the Marcionites, who believed that the God of the Old Testament was a villainous enemy of the God of the New Testament. On his travels, the author witnesses modern instances not only of tolerance and mutual respect but of syncretism: the shrine of a medieval Muslim saint in northern Syria at which Christians as well as Muslims come to worship and pray for cures; the Orthodox convent of Seidnaya where the priest steps carefully over bearded Muslim men on prayer mats and where Muslim women light candles in front of the icons and leave gifts for the nuns in thanks for babies.

Dalrymple sees the eastern Christians as the last surviving bridge between Islam and Western Christianity. Sadly, few in the West are aware of them or care about their decline.

Book review © 2007 Michael Breen