The classic forms of Eastern Christian mysticism appeared toward the end of the 2nd century, when the mysticism of the early church began to be expressed in categories of thought explicitly dependent on the Greek philosophical tradition of Plato and his followers. This intermingling of primitive Christian themes with Greek speculative thought has been variously judged by later Christians, but contemporaries had no difficulty in seeing it as proof of the new religion’s ability to adapt and transform all that was good in the world. The philosophical emphasis on the unknowability of God found an echo in many biblical texts, affirming that the God of Abraham and the Father of Jesus could never be fully known. The understanding of the role of the preexistent Logos, or Word, of the Gospel According to John in the creation and restoration of the universe was clarified by locating the Platonic conception of Ideas in the Logos. Greek emphasis on the vision or contemplation (theōria) of God as the goal of human blessedness found a scriptural warrant in the sixth Beatitude: “Blessed are the pure in heart, for they shall see God” (Matthew 5:8). The notion of deification (theiosis) fit with the New Testament emphasis on becoming sons of God and texts such as 2 Peter 1:4, which talked about sharing in the divine nature. These adaptations later provided an entry for the language of union with God, especially after the notion of union became more explicit in Neoplatonism, the last great pagan form of philosophical mysticism. Many of these themes are already present in germ in the works of Clement of Alexandria, written in about 200. They are richly developed in the thought of Origen, the greatest Christian writer of the pre-Constantinian period and the earliest major speculative mystic in Christian history.

Origen’s mystical theology, which made the union of God and man in Christ the pattern for the union of Christ and the believer, required a social matrix in which it could take on life as formative and expressive of Christian ideals. This was the achievement of early Christian monasticism, the movement into the desert that began to transform ideals of Christian perfection at the beginning of the 4th century. The combination of the religious experience of the desert Christians and the generally Origenist theology that helped shape their views created the first great strand of Christian mysticism, one that remains central to the East and that was to dominate in the West until the end of the 12th century. Though not all Eastern Christian mystical texts were deeply imbued with Platonism, all were marked by the monastic experience.

The first great mystical writer of the desert was Evagrius Ponticus (346–399), whose works were influenced by Origen. His writings show a clear distinction between the ascetic, or “practical,” life and the contemplative, or “theoretical,” life, a distinction that was to become classic in Christian history. His disciple, John Cassian, conveyed Evagrian mysticism to the monks of western Europe, especially in the exposition of the “degrees of prayer” in his Collations of the Fathers, or Conferences. Gregory of Nyssa, the younger brother of St. Basil the Great, sketched out a model for progress in the mystical path in his Life of Moses and, following the example of Origen, devoted a number of homilies to a mystical interpretation of the Song of Solomon, showing how the book speaks both of Christ’s love for the church and of the love between the soul and the Divine Bridegroom.

Perhaps the most influential of all Eastern Christian mystics is Pseudo-Dionysius, who was probably a Syrian monk of the 5th or 6th century and who wrote in the name of Dionysius the Areopagite, Paul’s convert at Athens. In the chief works of Pseudo-Dionysius, Mystical Theology and On the Divine Names, the main emphasis was on the ineffability of God (“the Divine Dark”) and hence on the “apophatic” or “negative” approach to God. Through a gradual process of ascension from material things to spiritual realities and an eventual stripping away of all created beings in “unknowing,” the soul arrives at “union with Him who transcends all being and all knowledge” (Mystical Theology, chapter 1). The writings of the Pseudo-Dionysius also popularized the threefold division of the mystical life into purgative, illuminative, and unitive stages. Later Eastern mystical theologians, especially Maximus the Confessor in the 7th century, adopted much of this thought but imbued it with greater Christological emphasis, showing that union with God is possible only through the action of the God-man.

Eastern mystics distinguish between the essence of God and divine attributes, which they regard as energies that penetrate the universe. Creation is a process of emanation, whereby the divine Being is “transported outside of Himself…to dwell within the heart of all things…” (Pseudo-Dionysius the Areopagite, On the Divine Names, iv. 13). The divinization of humanity is fundamental to Eastern mysticism.

Divinization comes through contemplative prayer, and especially through the method of Hesychasm (from hesychia, “stillness”), which was adopted widely by the Eastern monks. The method consisted in the concentration of the mind on the divine Presence, induced by the repetition of the “Jesus-prayer” (later formalized as “Lord Jesus Christ, Son of God, have mercy on me a sinner”). This culminated in the ecstatic vision of the divine Light and was held to divinize the soul through the divine energy implicit in the name of Jesus. Although much of this program appears in the writings of Symeon the New Theologian (c. 949–1022), a monk of Constantinople, it reached its most developed form in the works of Gregory Palamas (1296–1359), who defended the Hesychast tradition against its opponents. This rich form of Christian mysticism found a new centre in the Slavic lands after the conquest of the Greek East by the Turks. It experienced a flowering in Russia, beginning with the Philokalia, an anthology of ascetical and mystical texts first published in 1782, and continuing to the Revolution of 1917. Eastern Christian mysticism is best known in the West through translations of the anonymous 19th-century Russian text The Way of the Pilgrim, but noted Russian mystics, such as Seraphim of Sarov (1759–1833) and John of Kronshtadt (1829–1909), also became known in the West during the 20th century. Among mystic sects native to Russia, the Dukhobors, who originated in the 18th century among the peasants, resembled the Quakers in their indifference to outer forms and their insistence on the final authority of the Inner Light. They were severely persecuted and migrated to Canada early in the 20th century.

In the Eastern as in the Western church mystical religion was at times declared heretical. The earliest of the mystics to be denounced as heretics were the Messalians (Syriac for “praying people”) of the 4th century. They were accused of neglecting the sacraments for ceaseless prayer and of teaching a materialistic vision of God. Later mystics, both orthodox and suspect, have been accused of Messalianism.