According to a beloved and now generally disbelieved story, the Cross upon which Jesus suffered was discovered some three hundred years after the event by the saintly Helena, mother of Constantine the Great, Rome's first Christian emperor. For centuries, this story enjoyed the greatest vogue, blossoming into a full-blown Legend of the Cross which traced its genealogy all the way back to the Garden of Eden. With the waning of the Middle Ages, however, came new criteria for evidence, and with them a scholarly predisposition to dismiss the discovery, as well as the legend, as pure bunkum. Put together all the pieces of the True Cross, it became common to say, and one could float a fine freighter.

In the period of time between the Islamic conquest and the coming of the crusaders to Palestine in 1099, Christian pilgrims from East and West continued to visit the Holy Land, and particularly Jerusalem, by the licence of the Islamic government. Among the western visitors during this period at least half a dozen of them published accounts of their journeys. However, these accounts tell one virtually nothing about the life of the local Church, beyond the occasional list of shrines, churches, monasteries and the number of personnel assigned to them. As one modern scholar has remarked, ‘In the Patriarchate of Jerusalem the indigenous element is always half-hidden behind the crowds of pilgrims of every nationality…In the Holy City the resident aliens often outnumbered the Christian natives of Jerusalem, but in Palestine taken as a whole, the Syrians must always have been a majority.’

While it is incontrovertible that the Catholic faith exercised a profound influence on the lives of the common people of fifteenth-century England, it is equally apparent that many aspects of contemporary belief and practice will never be wholly clear. This is not simply for want of evidence but more the result of the limitations of the sources. It may, for instance, be assumed that contemporaries' religious priorities would be illuminated by close examination of their wills since these documents almost invariably deal with pious provisions intended to benefit testators' souls. But tolerably represented by surviving wills as the wealthy and town-dwelling classes of late medieval England are, analysis of these documents is treacherous. Just as the scribes who registered them certainly standardised the presentation of different testators' wishes, so probate procedures militated against even faintly unorthodox expression. Moreover, the proportion of a testator's movable or immovable estate represented in any given will is impossible to gauge, as a result of which no measure may be taken of any testator's devotion by comparison of his religious bequests with those made for other purposes. It must also be remembered that wills reveal nothing of the pious provision that testators undoubtedly made during their lifetimes for their own benefit. Neither do they convey any impression of what family or friends may have agreed to discharge for the benefit of a testator's soul. Late medieval wills are undeniably disappointing and frequently misleading.

There are several questions yet to be answered in the period of Italian religious history leading up to the Council of Trent. One particularly intriguing question is the part played by the Benedictine Congregation of Santa Giustina of Padua, generally known as the Cassinese Congregation. Historians have often observed some of these monks flitting like shadows around the fires of controversy, but what they were actually doing has remained obscure. They had connections with Contarini, Pole, Sadoleto and other spirituali; they gave hospitality to Pier Paolo Vergerio, bishop of Capodistria, before he fled into the Protestant camp; amongst them were many humanist educated biblical scholars, some of whom publicly expounded St Paul; the Congregation's chief spokesman at the Council of Trent was shouted down for what were taken to be his Lutheran sentiments; another monk was the prime author of the tract Il Beneficio di Cristo, later revised by Marcantonio Flaminio and published in 1543 with lengthy extracts from the 1539 edition of Calvin's Institutes woven into its text. It is not surprising that several historians, in common with a number of contemporary observers, have suggested that some of these Benedictines were strongly influenced by Reformation thought.

The history of the Russian Orthodox Church, especially in the modern imperial period (1700–1917), has been a woefully neglected field of scholarly research. That neglect antedates the collapse of the ancien regime in 1917, for pre-revolutionary historiography on the Church was neither abundant nor sophisticated; rarely did it produce more than myopic diocesan histories, fatuous accounts of the local seminary, or hagiographic paeans devoted to some prominent clergyman. The reasons for this neglect of so fundamental an institution in ‘Holy Rus’ are many – restricted access to ecclesiastical archives, difficulties in publication because of vigilant censors, but above all the intelligentsia's indifference to an apparently moribund and state-controlled institution. Paradoxically enough, Catholic polemicists, Orthodox Slavophiles, anticlerical intellectuals and reform-minded clergy all concurred – from different motives, for different reasons – in believing that the Church had become a mere instrument of the secular state, and that this change derived from ‘revolutionary’ and ‘Westernizing’ reforms in the Church imposed by Peter the Great in the early eighteenth century.