Researched by the Ignaria Editorial Team · Published 2026-05-27
The phrase "spiritual formation" is recent — popularized by twentieth-century writers — but the practice it describes is ancient. The apostolic church called it walking in the Spirit and continuing steadfastly in the apostles' doctrine and fellowship. The desert tradition called it purity of heart, cultivated through mortification of the passions and bodily discipline. The medieval mystics called it reforming the soul through stages — from reformation in faith to reformation in feeling, from self-knowledge to contemplative union with God. The Reformers called it mortification, growth in grace, and the goal of regeneration itself. John Cassian, Walter Hilton, Catherine of Siena, and John Calvin were not describing different realities — they were describing the same disciplined, corporate, Spirit-led life under different names. This entry traces the ancient roots of what modern evangelicals call spiritual formation.
The Biblical Foundation: Spirit-Led Life and Ecclesial Practices
The earliest Christian communities understood spiritual formation as a Spirit-directed life expressed through concrete ecclesial practices. Acts 2:42 records the fourfold pattern — apostolic teaching, fellowship, the breaking of bread, and prayer — as the normative rhythm of Christian existence, not optional enrichment. Paul distilled the same principle into the imperative to "walk in the Spirit" (Galatians 5:25), where "walk" denotes habitual conduct rather than momentary experience. James adds that when affliction strikes, the believer calls for the elders — prayer and anointing mediated through ordered ministry within the visible body (James 5:14). Together these texts establish that formation is neither purely interior nor individualistic: it is a corporate, embodied, and disciplined life in which apostolic doctrine, sacramental fellowship, and Spirit-led prayer converge.
Patristic Foundations: Mortification and Purity of Heart
John Cassian, writing in the early fifth century, translated the biblical call to walk in the Spirit into a systematic program of interior combat. The monk who would advance in prayer must first "thoroughly root out the feeling of wrath" — Cassian treats anger not as a minor fault but as a fundamental obstacle that distorts perception and blocks the soul's ascent. He further teaches that purity of heart determines the quality of prayer itself: "according to the measure of its purity, each mind is both raised and moulded in its prayers." The vision of Christ in contemplation is proportioned to the degree of detachment achieved. Bodily asceticism — fasting, vigil, affliction of the flesh — serves this interior contest by weakening the passions that resist the Spirit's governance. Formation is measured by progressive purification that enables clearer sight of the Lord.
Medieval Development: Self-Knowledge, Affective Virtue, and Ascent
Walter Hilton mapped the soul's journey from initial conversion to mature union with God, distinguishing "reforming in faith" — a stable moral life that resists deadly sin — from "reforming in feeling," which he calls "the highest state in this life." The latter requires prolonged exercise and special grace; affective transformation is its mark, when the soul "loveth virtues because they be good in themselves." Catherine of Siena figures the soul's formation in the image of the "house of self-knowledge," where, after passing through the doctrine of Christ crucified, it remains in watchful prayer separated from worldly consolations. Bonaventure frames the ascent as Jacob's ladder: sin deforms nature; prayer and regenerating grace restore the soul's capacity to mount from external to internal realities. Albertus Magnus sets the goal: "the whole life and the desires of the heart form one unbroken prayer." Formation is complete not when duties are performed but when prayer becomes the continuous orientation of existence.
Reformation and Post-Reformation Continuity: Mortification, Growth, and Spiritual Worship
John Owen defined mortification in terms that echo Cassian: it is "the weakening and graduate extirpation or destruction" of sin in its roots and operations, so that the soul is "set at liberty to act universally from the contrary principle of spiritual life and grace." Matthew Henry describes divine grace as dew on the soul — gentle, continuous nourishment producing growth both visible (like the lily) and hidden (like the cedar's root). Thomas Watson insists that the spiritual part of worship is "the fat of the sacrifice" — because God is Spirit, formation aims at engagement of the heart rather than outward form alone. John Calvin frames the goal of regeneration as bringing the believer's life "into concord and harmony with the righteousness of God, and so confirm the adoption by which they have been received as sons." Across all these voices the Reformation preserves what the patristic and medieval traditions established: formation is disciplined, gradual, Spirit-dependent, and aimed at likeness to God.
What the primary sources show
"And they continued stedfastly in the apostles' doctrine and fellowship, and in breaking of bread, and in prayers." — The fourfold apostolic pattern is not optional enrichment but the normative structure of Spirit-led life, presenting formation as the ordinary consequence of remaining steadfast in these practices rather than an extraordinary achievement reserved for spiritual elites.
"For according to the measure of its purity, each mind is both raised and moulded in its prayers if it forsakes the consideration of earthly and material things... and enable it with the inner eyes of the soul to see Jesus either still in His humility and in the flesh, or glorified and coming in the glory of His Majesty." — Cassian's core principle: purity of heart is the condition that determines the quality and depth of the soul's vision of Christ in prayer.
"Wherefore the athlete of Christ who strives lawfully ought thoroughly to root out the feeling of wrath." — Cassian treats anger not as a minor fault but as a fundamental obstacle blocking spiritual ascent; mortification of wrath is prerequisite, not optional refinement.
"But reforming in feeling is the highest state in this life that the soul can come to." / "This is the conforming of a soul to God, which cannot be had unless it first be reformed by some perfection of virtues turned into affection; which is when a man loveth virtues because they be good in themselves." — Hilton's developmental map: moral stability (reforming in faith) prepares for affective transformation (reforming in feeling), where virtue becomes the soul's spontaneous orientation.
"When the soul has passed through the doctrine of Christ crucified, with true love of virtue and hatred of vice, and has arrived at the house of self-knowledge and entered therein, she remains, with her door barred, in watching and constant prayer, separated entirely from the consolations of the world." — Catherine figures formation as an enclosed, watchful withdrawal into self-knowledge that prepares the soul for union with God.
"This, I say, is the end of all perfection — that the soul may become so purified from every earthly longing, and so raised to spiritual things, that at last the whole life and the desires of the heart form one unbroken prayer." — Albertus names the goal of formation: not discrete devotional acts but a continuous orientation of the heart toward God that becomes the very form of life.
"It is the weakening and graduate extirpation or destruction of them, in their roots, principles, and operations, whereby the soul is set at liberty to act universally from the contrary principle of spiritual life and grace." — Owen's Reformed account of mortification: the Spirit gradually destroys the root of sin so that the soul may act freely from the principle of grace — gradual, Spirit-dependent, and aimed at liberation for righteous action.
"We have said that the object of regeneration is to bring the life of believers into concord and harmony with the righteousness of God, and so confirm the adoption by which they have been received as sons." — Calvin defines the goal of spiritual formation in covenant terms: regeneration aims at likeness to God that confirms sonship, echoing the medieval theme of union while grounding it in a Reformed theology of grace.