Spiritual formation has become a hot topic in Christian theology. Over the past half-century, a cottage industry in evangelicalism has emerged around practices, habits, and intentional patterns of discipleship—often traced, symbolically, to the publication of Richard Foster’s Celebration of Discipline in 1978. This renewed interest is frequently driven by dissatisfaction with “thin” accounts of the Christian life that reduce discipleship either to doctrinal assent or to episodic moral effort. In response, many have emphasized holistic habits, intentional practices, and even personal “rules of life” as means of apprenticing to Jesus and inhabiting the kingdom in the present.
While this renewed attention is a welcome corrective to “thin” discipleship, it has also generated a certain conceptual fog. Many contemporary models of formation appear more like psychological self-help or therapeutic habit-stacking than distinctively Christian sanctification. And some worry, not without reason, that this new passion for “thick” discipleship defined by ascetical practices can cultivate spiritual pride rather than Christ-reliant Christlikeness. To clear this fog, we need a precise grammar that can name what is being formed, into what pattern, by what agency, and for what purpose. For this, we can turn to a classic analytical tool: Aristotle’s Four Causes. This will help us clarify just exactly what Christian spiritual formation is.
The Material Cause: The Human Person, Fallen and Redeemed
The material cause concerns the matter that is shaped—the “stuff” upon which formation works. In Christian spiritual formation, that material is the human person: embodied and rational, desiring and relational; created in the image of God; fallen through sin; and redeemed in Christ.
Human beings were created to know, love, and glorify God—to live in obedient fellowship with their Creator. Yet sin has profoundly misshaped this material. Our loves are disordered, our wills bent inward, our imaginations captured by false objects of worship. Scripture therefore describes sin not merely as rule-breaking (though never less than this), but as deformation: a corruption of our created nature, rendering us less than—and often opposed to—what we were made to be as God’s image bearers.
For this reason, Christian spiritual formation is always also counter-formation—a point profitably emphasized in much of the recent literature. Many fail to recognize that they are always being formed by their habits and the culture around them. This is why Paul exhorts the Romans to fight back against the formational pressures of the world, and instead intentionally seek to be transformed according to the will of God (Rom. 12:1-2).
Christians may choose whether to be intentional about formation, but they cannot choose whether to be formed. As Bob Dylan memorably put it, “You gotta serve somebody.” And no one can serve two masters (Matt. 6:24). What we serve, we imitate; what we behold, we become (Ps. 115:8; 135:18; Hos. 9:10; 2 Cor. 3:18). Spiritual formation is therefore a battlefield. Sin seeks to reign in the self (Rom. 6:12–14). The body must be disciplined lest it defect (1 Cor. 9:24–27). There is an internal war within the person (Rom. 7; 1 Pet. 2:11), while external pressures from the world and the devil press in relentlessly (1 Pet. 5:8–9).
At the same time, Christian formation does not begin with us on our own, starting from merely a negative or neutral standpoint. Those who belong to Christ are not simply sinners attempting improvement; they are new creatures united to him. “If anyone is in Christ, he is a new creation” (2 Cor. 5:17). Through union with Christ, believers have died to sin and been raised to new life (Rom. 6:1–11; Gal. 2:20; Eph. 2:4–6).
This creates the defining tension of Christian formation. Our remaining fallenness means formation is necessary; our newness in Christ means formation is possible. The old self has been decisively judged and crucified, yet its habits and impulses persist. The new self has been granted in Christ, yet this must be progressively “put on” through renewed patterns of life (Eph. 4:22–24; Col. 3:9–10). Spiritual formation, then, concerns the comprehensive reshaping of the whole person—mind, body, habits, and desires—according to a reality that has already been established in Christ.
The Formal Cause: Christ as the Pattern of True Humanity
If the material cause identifies what is being formed, the formal cause identifies into what shape. In Christian theology, the answer is unequivocal: Jesus Christ himself, as the true image of God.
Christ is “the image of the invisible God” (Col. 1:15), “the exact imprint” of God’s nature (Heb. 1:3), and the one in whom God is definitively made known (John 1:18; 14:9). God’s redemptive purpose is that his people be “conformed to the image of his Son” (Rom. 8:29). Formation, therefore, is not self-invention but conformity to a given form.
This entails a Christological anthropology. As Karl Barth famously argued, theological anthropology must be grounded in Christology (see Church Dogmatics III/2, § 45.1). We do not determine the meaning of humanity in abstraction and then apply it to Jesus; rather, Jesus Christ reveals what humanity truly is. As Barth insists, the humanity of Jesus is the criterion for understanding humanity as such: “When we ask: What is humanity, human creatureliness? we must first ask: What is its basic form? … Our criterion in answering this question is the humanity of the man Jesus” (CD III/2, § 45.2). This is echoed in Vatican II’s Pastoral Constitution on the Church in the Modern World, Gaudium et spes: “only in the incarnate Word does the mystery of humanity” come fully into view; “Christ … fully reveals man to man himself and makes his supreme calling clear” (§ 22).
Christ is not only the image but also the archegos—the pioneer and perfecter of salvation (Heb. 2:10; 12:2). He goes before us as the pattern into which we are being shaped. Scripture therefore repeatedly calls believers to imitation: to walk as he walked (1 John 2:6), to follow in his steps (1 Pet. 2:21), and to be imitators of God as beloved children (Eph. 5:1).
Spiritual formation is thus irreducibly christological. It is the restoration of true humanity through conformity to Christ.
The Efficient Cause: The Spirit’s Work Through Human Participation and Means
The efficient cause concerns agency and instrumentality—who and/or what brings about transformation. Scripture presents sanctification as neither passive quietism nor autonomous self-improvement. It is a Spirit-empowered process that involves real human participation.
Believers are repeatedly exhorted to act: to put off the old self, to renew the mind, to press on toward maturity, to present their bodies to God (Rom. 12:1–2; Eph. 4:22–24; Phil. 3:12–14; Col. 3:9–10). These imperatives assume agency, effort, and intentionality. Spiritual formation demands our active engagement.
Yet this effort is never self-generated. “Work out your own salvation,” Paul writes, “for it is God who works in you, both to will and to work for his good pleasure” (Phil. 2:12–13). The primary efficient cause of transformation is the Holy Spirit—the Spirit of Christ given to those who belong to him (Rom. 8).
The Spirit applies Christ’s finished work to believers, uniting them to Christ and enabling obedience from the inside out. Abiding in Christ is the controlling metaphor (John 15): apart from him we can do nothing; united to him by the Spirit, we bear fruit.
Crucially, the Spirit works through means. Chief among these is the Word of God, which trains believers in righteousness and equips them for good works (2 Tim. 3:16–17). Faith comes by hearing (Rom. 10:17), and sanctification occurs through truth (John 17:17). Prayer, sacrament, and the shared life of the church likewise function as Spirit-appointed instruments of formation.
This last means is important to highlight, because it is often neglected in literature about spiritual formation. The ecclesial context is key. This is clear in Ephesians 4, in its discussion of the gifts given by the risen Christ through the Spirit to the church. Such diverse gifts were given to build up the body, so that Christians “attain to the unity of the faith and of the knowledge of the Son of God, to mature manhood, to the full measure of the stature of the fullness of Christ.” Members “speak[] the truth in love” to help us all “grow up in every way into him who is the head, into Christ.” Thus, we see that formation is a communal task, as well.
The Final Cause: Glory, Communion, and Joy
The final cause concerns the ultimate purpose of formation. Scripture consistently names this end as the glory of God and the joy of his people.
God chose his people “that we should be holy and blameless before him… to the praise of his glorious grace” (Eph. 1:4–6). Transformed lives are ordered toward divine praise, displaying God’s excellence before the world (1 Pet. 2:9). At the same time, holiness is not opposed to happiness. Holiness is a requirement to see God (Heb. 12:14; cf. Matt. 5:6, 8), and to see God is joy (Ps. 16:11). Jesus explicitly connects obedience, abiding, and fullness of joy (John 15:11).
Formation is therefore teleological through and through. It is ordered toward deeper communion with God and toward a life that reflects his character in the world. Importantly, this end is not merely individual. God is forming a holy people—a community whose shared life embodies his purposes for humanity. As Ephesians 4 makes clear, the church is both the context and the instrument through which believers grow into the fullness of Christ.
Conclusion
The four causes together provide a coherent theological grammar for spiritual formation.
The material cause is the human person, fallen yet renewed in Christ.
The formal cause is Jesus Christ, the true image and pattern of humanity.
The efficient cause is the Holy Spirit, working through human participation and ordained means.
The final cause is the glory of God and the joy of communion with him.
Taken together, the four causes provide a coherent theological grammar for spiritual formation. Such a grammar guards formation from the twin distortions of bespoke, therapeutic self-optimization on the one hand, and moralistic, self-righteous ambition on the other. Instead, it reminds us that we are given a form not of our own making, and that we are not left to generate transformation by our own power. There is much to affirm in the renewed evangelical concern to address what Richard Lovelace famously termed the “sanctification gap,” particularly in its resistance to both easy-believism and hyper-rationalist reductions of the Christian life. Yet this gap will be closed not by the accumulation of techniques, but by recovering a thicker, more theologically ordered account of sanctification itself.
