The synergistic nature of sanctification in the Christian life
Rev. Dr. Douglas Olds
Sanctification is our inevitable but free response to the faith-enlivening grace we encounter. It progressively settles the contest between the two dimensions of moral consciousness: death and life—between agon (striving, manipulation, and violence) and shalom (peace, virtue, and charity). It is initiated and guided by the primary cause—the Spirit--who dynamically coaxes the secondary, created human agent’s efforts and beliefs into alignment with those ultimately, divinely willed.
Grace enables moral effort that, when conscientiously processed by the unbound-from-sin believer—as a commitment to strengthen obedience--results in moral progress and growth in sanctification. God is the ultimate enabler and author of sanctification, while we are the secondary participants in the operation of God’s grace in this world and in our lives. By keeping our eyes on Christ, we can judge and correct our moral efforts by the standards he set, taught, and exemplified in his perfect and sinless life revealed in the Gospels.
Barclay (2017, 3.4 emph. added) notes the achievements of John Calvin in describing the synergy of God’s grace as primary cause and the believer’s effort as secondary cause, operationalizing the sanctifying agency of God with the believer following in cooperation and obedience:
Calvin insists that justification is effected through faith without works, he is equally insistent that it is not devoid of good works, and he devotes considerable attention to the process of sanctification. Christ was given to us by God’s generosity, to be grasped and possessed by us in faith. By partaking of him we principally receive a double grace: namely, that being reconciled to God through Christ’s blamelessness, we may have in heaven instead of a Judge a gracious Father; and secondly, that sanctified by Christ’s Spirit, we may cultivate blamelessness and purity of life (Inst. III.11.1). These two operations are distinct but inseparable…[a] combination of motifs in 1 Corinthians 1:30 is significant: citing this verse, Calvin insists, “Christ justifies no one whom he does not at the same time sanctify” (Inst. III.16.1). Calvin is unwilling to follow the Lutheran distinction between inner saving faith and outer works of service, because the believer’s good works are integral to participation in Christ, whose purpose is to conform believers into his image (Rom 8:29) and thus to transform them into some approximation of the holiness of God (Inst. III.8.1). Calvin’s task — and considerable achievement — is to position a life of good works within the scheme of salvation, without making these works instrumental in obtaining or “meriting” grace, that is, without compromising the priority and incongruity of grace…[H]e laid the foundation for a Protestant theology of grace that envisaged an extended narrative of moral progress as an integral element of the life of faith…While the law sets an impossibly high standard for those unconnected to Christ, its promised blessings are not empty, but are granted to “the works of believers” (Inst. III.17.3). Indeed, the law’s “third use” [see esp. Rom. 7.25], in instruction for Christian believers, can be considered its principal function (Inst. II.7.12). 114 This forges a harmony between “law” and “gospel” in a fashion quite alien to Lutheran discourse. Obedience to God emerges as the hallmark of the Christian life, even if this is carefully glossed as the voluntary submission of sons to a benevolent Father (Inst. III.19.5). With such emphasis on good works as the purpose of salvation, Calvin also … therefore … characteristically insists that the believer’s works, however good, remain “stained” by the pollution of sin.
This synergy in sanctification is the work of the primary cause (God in Christ) carried out by the cooperation of the Holy Spirit-guided person as the secondary cause. In this, the perfect primary cause is never the agent of sin. Holdover eruptions of sin are the responsibility and defect of the secondary cause when the Holy Spirit is ignored or opposed. Before justification, the secondary cause of action (the person) is under the delusion of an alien and evil imposter causation that claims, falsely, that it is primary. That leads to the sins of paganism—finding in nature or in false gods and idolatry a sanction or warrant for continuing in sin. Sanctification is the process of replacing the imposter claims of primary causation with that of ontological truth and accordance with it. Sanctification advances as the person increasingly obeys the promptings of the Holy Spirit and has fewer regressions into past patterns of resistance to these promptings. Sanctification has the secondary cause of earthly events taking on more and more of the nature of the primary cause, bringing about a more recognizably pure primary causation to the human's response to contingencies, thereby furthering the kingdom of God.
Barclay, John M. G. Paul and the Gift. Grand Rapids: Eerdmans. 2017.
 An OT phenomenology of spiritual activity that fills or completes is indicated by Ezra 1.1 where the spirit of Cyrus is agitated to complete the Word of God. The verb “agitated” that fills or is fulfilled in Cyrus refers back prophetically to its use in Isa. 45.13 and Jer. 51.11 (Schnittjer 2006). God’s Spirit “clothes” the problematic Gideon (Judg. 6.34), suggesting outer completeness only, an externalized, functional kind. In NT times, the human soul was recognized as the site of God’s active purpose. With the Holy Spirit’s sending to the Church in Acts 4, the comprehensive and filling inner effect of the Spirit processes to bring about God’s purposes.