The expansion of Catholic Christianity north and west of the Mediterranean Basin through mass conversions of peoples as a result of the baptism of their king or chieftain had the net effect of generating mass nominalism. To put it simply, many of the new converts were Christian in name only.
Mass and indirect conversions were not unique to medieval Christian missions.
Recall that in the book of Acts (chapter 2) some 2,000 are said to have been converted to the faith as a result of Peter’s speech. In Acts chapters 10 and 11, Peter baptizes the first Gentile, a centurion named Cornelius who, as befit the Roman paterfamilias, had his whole household, wife, children, servants and slaves baptized as well.
Christians, even those who had known Jesus, were not instantly enlightened men and women of our time (although arguably our time is not so enlightened). They were people of theirs.
While the manner of conversion in some cases involved some peer pressure at a minimum, or even coercion of the sort we can only imagine at the hands of the average barbarian chieftain, it was based on a widely accepted principle, which was accepted long after the Middle Ages and even by leaders of the Protestant Reformation as late as the 17th century.
Cuius regio, eius religio is a Latin phrase that literally means “whose realm, his religion,” meaning that the religion of the ruler should dictate the religion of those ruled.
Of course, nominal European Christians would be very unlikely to march to martyrdom singing hymns of praise as had their predecessors under Roman persecution.
The new tepid faith was evident in the behavior of the Christian kings and chieftains—as we saw earlier in the words of Gregory Dix (see Enter the Barbarians)—but also in that of ordinary people in matters religious, in particular the Eucharist.
Faced with desecration of consecrated wine through drunkenness or coarse and clumsy manners leading to spillage, the Church experimented with a vast array of methods of dispensing wine. In despair, clerics in the West opted to withhold communion in both species, reserving the Blood of Christ for those in the sanctuary area surrounding the altar, mostly clerics or clerics in training. It was argued that the Body of Christ in the consecrated bread implicitly contained the Blood, as flesh and blood are as one.
Moreover, nominalism brought about a decline in the reception of communion, even in the bread species alone. This has been studied by reviewing the records of communion bread production by monasteries and purchases by dioceses.
In response to the lukewarm faith of an arguably ill-prepared laity, clerics began to devise a series of clever rules and devices to suffuse the ordinary lives of Catholic Christians in Europe with acts that might elicit the true inner disposition of conversion that was missing.
This is the source of rigorism, which eventually devolved into widespread mandatory fasting and church attendance at various times of the year. It is also what propelled the Church to combat the ignorance of the laity with artistic works, such as stained-glass windows, statues of saints and awe-inspiring Gothic cathedrals pointing upward, to God.
All of this did not occur at once, nor systematically, as we shall see.