The beer rehabilitated by the Church after the Christianisation of Europe.
The Roman Church has accommodated itself to beer, while reaffirming the imprescriptible and unchangeable role of wine in communion each time that beer has been proposed as a substitute for wine in a sacrament, arguing that beer suited to the geographical constraints and the expansion of Christianity. Beer will forever remain a secular beverage.
The Roman Church will ensure that there is no resurgence of secular ceremonies that put beer at the centre of communal rites, under the guise of enthronements or banquets organised by guilds or friendly societies.
Great Northern Beer Drinkers. Facsimile of an engraving from the History of the Northern Countries,
Olaus Magnus, Anvers 1560.
But a rehabilitation of beer is underway in the secular domain in the heart of the long Christianised regions of Europe, north of a line running roughly from the Danube to the Loire. Beer is rehabilated by the Franks, especially when they founded a great western European empire known as the Carolingian empire in the mid 8th century. This Europe is covered with churches and monasteries. Focused on prayer and study, abbeys and monasteries also had to offer shelter and meals to the poor, pilgrims and guests passing through: charity and the propagation of the faith.
In 540, St Benedict established the rule of self-sufficiency for monastic communities. Manual work complements intellectual activity (study and copying of religious texts) and prayer (Rule 48.8: If, however, the needs of the place, or poverty should require that they do the work of gathering the harvest themselves, let them not be downcast, for then are they monks in truth, if they live by the work of their hands, as did also our forefathers and the Apostles. However, on account of the faint-hearted let all things be done with moderation.).
When he retired to Mont Cassin in Italy, St Benedict says nothing about beer. But his rules inspired many monastic orders and set the rules for the use of beer within them. They also favoured the installation of the brewery inside the abbeys, because according to the rule 66, 6-7: " If it can be done, the monastery should be so situated that all the necessaries, such as water, the mill, the garden, are enclosed, and the various arts may be plied inside of the monastery, so that there may be no need for the monks to go about outside, because it is not good for their souls. But we desire that this Rule be read quite often in the community, that none of the brethren may excuse himself of ignorance. " (St Benedict's Rule).
The rule of St. Benedict, written for Italian monasteries, only mentions wine and says nothing about beer: " However, making allowance for the weakness of the infirm, we think one hemina (1/2 litre) of wine a day is sufficient for each one " (Rule 40). It will be adapted according to Central and Nordic European countries. Some bishops or abbots like Theodomar will formally forbid monks to drink wine. Others like St St Sturmius (715-779) will ban wine, a beverage considered too alcoholic, and will have it replaced by a low density beer. From the 8th century, the Church, paradoxically, promotes brewing within its own institutions. Beer became in its view a healthy and low alcoholic secular beverage. The monasteries are allowed to set up their own breweries. Europe is now Christianised. Beer no longer competes with wine in religious and priestly terms.
In addition, the Westerner Christian Church has become the owner of huge land estates over the course of 4 centuries. Part of the agricultural production is in its hands, especially that of cereals. This explains why the more or less self-sufficient economy of the abbeys and monasteries of Western Europe found in the brewery a way to use its grain reserves.
In order to find a technical solution to a theological problem - separation of the laity and the religious (outside/inside the monastery), and at the same time sharing the same space (charity/duties of hospitality) - the monks will become brewers.
The problem they have to solve is the following: how to brew and tap for the monks on the one hand, and lay people and pilgrims on the other, 2 or 3 different qualities of beer, from the strongest to the weakest in alcohol, with the same brew, the same batch of grains?
The solution: soak the mash in large vats and withdraw each juice (wort) of decreasing density, each juice or mash being fermented separately in barrels or tuns. The technical principle is simple: the first juice from the mash is the sweetest, the second less - after pouring a further quantity of hot water over the mash. The last rinse, with very little sugar, will produce a beer that is very low in alcohol and not very nutritious. This technique involves double-bottomed wooden soaking vats to allow the hot water to pass through the mash several times.
In this way, three qualities of beer can be brewed all year round: a higher quality (prima melior) is reserved for abbots and prestigious guests of the Frankish aristocraty, a medium quality (secunda) accompanies the daily meals of the monks, a lower quality (tertia) for the abbey's hostelry, the many lay people who work in the monastic agricultural estates, pilgrims and the needy.
In a curious reversal of values, the Catholic Church will allow the consumption of beer during Lent when wine is forbidden, assimilated to a luxury beverage, which it actually is.
The beer, denigrated as a source of drunkenness, of debauchery and orgy in the times of "barbaric paganism", is rehabilitated as a "lean" drink in the Catholic calendar. But this is now for healthy reasons, not theological. The blessing of the beer, attributed to St Arnoult de Soissons, confers no sanctity upon this fermented beverage: Bless, O Lord, this new beer, it hath pleased thee to take from the tenderness of the grain; can it offer a salutary remedy to mankind : grant that, by the invocation of Thy holy name, anyone who drinks it covers the health of the body and protection of his soul. In the name of Christ our Lord. Amen. (Rituale Romanum no. 58).
Finally, in the grim hours of great epidemics or religious unrest, the legend of certain saints will incorporate beer as the object of miracles. St Arnulf of Metz (582-641) is honoured for having blessed (himself or his relics) beer vats, saved beer brews from corruption and offered the population a healthy beverage, becoming patron saint of the brewers of Lorraine. In medieval Europe, brewers' guilds were sure to find a patron saint: Arnold of Soissons/brewers of Liège, St Amand/brewers of Maastricht (†679), St Martin/brewers of Ghent, St Boniface (680-754)/ brewers of Friesland (Netherlands), St Peter of Verona/Brewers of Cologne, St Médard/Dieppe and Flanders, St Wenceslas(927)/Bohemia, St Brigid of Kildare (457-525)/Ireland, Augustin d'Hippo (Tunisia), Nicolas de Myra (Turkey), St Colomban (543-615)/Switzerland, etc.
The feature that connects these holy men and women to beer is to be found in their exemplary religious life, or an episode related to preaching the Gospel, more rarely in the martyrology.
 The question will be raised again in the 16th century with the Spanish and Portuguese colonisation of the Americas, and in the 19th century by the Christian missions in Africa and Asia. On each of these continents, the settlers found native beers that were considered as good as European beers or wines. The response of the Roman Church will not vary: Cultivate the Lord's vines, literally and figuratively. This implies that no native beer, no other fermented beverage, will take the place of wine in the sacraments, especially the Eucharist.
 « It was decided by all unanimously that among them there should be no strong drinks which could intoxicate, but that weak beer should be drank » (Eigil de Fulda, Vita Sancti Sturmis, quoted by Max Nelson 2005, The Barbarian's Beverage, A History of Beer in Ancient Europe, p. 101). Lat. consensu omnium decretum est, ut apud illos nullo potio fortis quae inebriare possit, sed tenuis cervisia, biberetur.
 Arnold of Soissons. Latin: Bene dic, Domine, creaturam istam cerevisae, quam ex adipe frumenti producere dignatus es: ut sit remedium salutare humano generi: et praesta per invocationem nominis tui sancti, ut, quicumque ex ea biberint, sanitatem corporis, et animae tutelam percipiant. Per Christum Dominum nostrum. Amen.
 In the 11th century he founded St. Peter's Abbey in Oudenburg (Flanders) and began to brew beer, a beverage as important as water in the Middle Ages, the consumption of which he boasted to the peasants for its sanitary properties.