In the Middle Ages religio meant not only a system of beliefs or practices connecting humanity with the divine, but also a way of living in community in devotion to God. It is not therefore surprising that most of the Medieval Latin works that could be classified as ‘religious’ were written by and for members of monastic or similar communities.

Firstly, there are the rules by which such communities would be constituted. The two most famous are the Benedictine rule and the Augustinian rule, but various adaptations of these to particular cicrumstances or houses are found from Britain, from the tenth-century Regularis concordia Anglicae nationis monachorum sanctimonialiumque to later custumaries and observances from such houses as Westminster, Barnwell, and St. Augustine's Canterbury. Penitentials, the deliberations of councils and synods, and many of the letters of such authors as Alcuin and Anselm also deal with the theory and practice of communal life.

Then there is a great outpouring of works intended to assist the community in their devotions. We have several collections of hymns and other devotional poetry, both anonymous and by authors such as Bede, Stephen Langton, and John of Howden. These could be used either in communal worship or privately, as could prayers and meditations such as those written by, for example, Anselm. From the more public or communal religious sphere we have liturgical texts and the great collections of sermons and homilies by authors such as Bede, Ailred of Rievaulx, and John of Ford, among many others. Closely related to the sermons and homilies we find numerous works of Biblical exegesis, by Bede, Alcuin, and many others. 

Models and inspiration for religious life were provided by accounts of saints' lives and their miracles, such as those found in the Nova Legenda Angliae, the Vitae Sanctorum Britanniae et Genealogiae and the Vitae Sanctorum Hiberniae. Also inspirational and devotional were works of theology, such as Ailred of Rievaulx's Speculum caritatis and De spiritali amicitia, or Adam Scot's De tripartito tabernaculo and De quadripartito exercitio cellae, which were written to build up the faith of the individual member of the community.

But few parts of life escaped religion entirely. Philosophical and scientific writings explored the universe God created. The new universities were also formed round communal life. Historians sought for morals and examples of God's providence. The monastic and cathedral communities had to administer themselves and their properties, as did the secular church, producing large quantities of administrative documents dealing with building works, estate management, and the other practicalities of day to day life. All these are well represented among our texts.

However, the religious life was not static and immutable. As the Middle Ages went on, the bonds of community became less strong and devotional works tended to become more individual. The fourteenth-century hermit Richard Rolle wrote the Incendium amoris and other works based on his solitary lifestyle, the English Ancrene Riwle, written for anchoresses, was translated into Latin, and there are even works written expressly for the laity, like the Speculum laicorum. This more individual approach also brought its problems. Heresy, which had not been a major them in religious writings since Alcuin's attacks on the beliefs of Elipandus and Felix, again became a serious concern in the fourteenth century, as witnessed by the Fasciculi Zizaniorum and the works of the controversial theologian John Wyclif, and the DMLBS's period extends far enough for some of our latest works to touch on the Reformation — whether from the point of view of Catholic reformers like Thomas More, or of Protestant ones like John Jewel. The fact that a book like the St Andrews Formulare contains examples both of a sentence condemning a heretic (in 1540, no. 469) and of a commission for the trial of witches (c1542, no. 438) speaks eloquently of the nature of the times.