Middle English literature was profoundly influence by medieval theology and philosophy. One critic has said that no other faith in history is distinguished by so prolonged and rich a debate over the nature of God and man as that which occurred from the early Greek and Latin apologists through the middle ages. Another has said that it was Christianity that kept philosophy alive and not the reverse.

Chief among the scholastic influences on the middle ages was the work of St. Augustine (354­430), Bishop of Hippo and a momumentally important work by Boethius (480­525), The Consolation of Philosophy. The Platonic conception of God as the principle of absolute being underlies Augustine's Christianity. Motivated by love, God created the universe, the angels, man, and all lower creatures. Each earthly creature represent both matter and form, the latter being the image of the divine idea and that which confers eternal existence. Man, composed of body and soul, can recognize the divinity in his soul as well as the omniscience of God when he considers such of his own qualities as his urge to seek the truth or his appreciation of beauty. From man's point of view, the whole of the visible creation serves as a means of understanding God­­a function that is basic to the medieval attitude toward the universe and toward Scripture.

The Consolation of Philosophy is an imagination conversation between Boethius, in prison and out of favor with the ruler of Rome, and his old "nurse," Lady Philosophy who materializes before him in the midst of his distress. In discoursing on the mutability of the things of this world, Lady Philosophy speaks in the person of Dame Fortune and emphasizes that the wise man never assumes that the gifts of fortune­­beauty, health, prosperity, high rank­­are his to keep. She also instructs him about the human will, which is free even though man must exist in a world created and governed by an omniscient God. God's omniscience and man's free will are reconciled in traditional Platonic terms. The key concept is the "simplicity" of God, who dwells beyond time. That which appears to man as bound by past, present, or future is to God embodied in the single instant of his creation. Thus, man's freedom of choice is not constrained by God's foreknowledge. This particular theme, God's providence vs man's free will, occurs time and again in middle English literature including many of The Canterbury Tales. Chaucer's fullest treatment, however, comes in his Troilus and Criseyde.

Another significant religious movement was mysticism, at the other end of the scale from what we might call the scholasticism of Augustine and his followers. Represented by someone like Bernard of Clairvaux (1096­1141), mysticism proceded from the principle that God in His infinity was totally beyond human intellect. Nevertheless, through the discipline of humility, compassion, and, finally, utter surrender to contemplation, a person might rise to a sense of participation or union with God. The true quality of this experience is incommunicable, yet the mystic is able to describe the various stages of the "way" and by analogy to sensory experiences such as sweetness, warmth, and joy, convey after a fashion the nature of the inner goal he seeks.

The religious literature of the middle ages is predictably moral and didactic. Much of it deals with doctrinal matters, decrees of church councils, and directives from bishops. A good Christian was have known by heart the Lord's Prayer, Hail Mary, and the Apostle Creed; these texts were preached on long and often.

In addition to the 10 Commandments and the seven sacraments (baptism, confirmation, Eucharist, penance, marriage, priestly orders, and unction), two other topics were often considered by the local priest: the seven virtues and the seven deadly sins. The seven virtues combined the four cardinal virtues (from classical writers)­­temperance, fortitude, prudence, justice­­and the three theological virtues­­faith, hope, and love.

The development of a list of seven especially damning sins is shadowy at best. The church in the Middle Ages taught that there were two major classifications of sins: venial and mortal. A venial sin, though tending to injure one's spiritual life, did not involve eternal damnation; instead, a venial sin hindered one's attempt to experience fully God's love. A mortal sin, however, did involve eternal damnation since such a sin was a willful violation of the known laws of God; a mortal sin cut one off from the love of God and resulted in the death of the soul. Early church fathers (Hermas, Tertullian, Augustine), while never actually listing specific mortal or "deadly" sins, did suggest that some sins were worse than others, perhaps, with I John 5:16­17 in mind:

If anyone sees his brother committing a sin not leading to death, he shall ask and God will for him give life to those who commit sin not leading to death. There is a sin leading to death; I do not say that he should make request for this. All unrighteousness is sin, and there is a sin not leading to death.

What eventually resulted, therefore, were numerous lists of especially harmful sins. However, the list that came to be most influential in the church was the one developed by Gregory the Great (540­605) and was characterized by its Latin acronym, saligia:

superbia (pride)

avaritia (greed)

luxuria (luxury, later lust)

invidia (envy)

gula (gluttony)

ira (anger)

acedia (sloth)

As well as their frequent appearance in church literature, the frequent reference to these seven deadly sins testifies to their importance. For example, William Langland's Piers Plowman, Dante's Divine Comedy, Chaucer's "Parson's Tale", and Spenser's The Fairy Queen devote serious attention to these sins.