Piety (pietas) is one of the major themes of John Calvin's theology. His theology is, as John T. McNeill says, "his piety described at length." He was determined to confine theology within the limits of piety. For Calvin, theology first of all deals with knowledge—knowledge of God and of ourselves—but there is no true knowledge where there is no true piety.
For Calvin, pietas designates the right attitude of man toward God, which includes true knowledge, heartfelt worship, saving faith, filial fear, prayerful submission, and reverential love. Knowing who and what God is (theology) leads to right attitudes toward Him and toward doing what He wants (piety). Calvin writes, "I call 'piety' that reverence joined with love of God which the knowledge of his benefits induces." This love and reverence for God is a necessary concomitant to any knowledge of Him and embraces all of life. Calvin says, "The whole life of Christians ought to be a sort of practice of godliness."
The goal of piety, as well as the entire Christian life, is the glory of God—glory that shines in God's attributes, in the structure of the world, and in the death and resurrection of Jesus Christ. Glorifying God supersedes personal salvation for every truly pious person. The pious man, according to Calvin, confesses, "We are God's: let us therefore live for him and die for him. We are God's: let his wisdom and will therefore rule all our actions. We are God's: let all the parts of our life accordingly strive toward him as our only lawful goal."
But how do we glorify God? As Calvin writes, "God has prescribed for us a way in which he will be glorified by us, namely, piety, which consists in the obedience of his Word. He that exceeds these bounds does not go about to honor God, but rather to dishonor him." Obedience involves total surrender to God Himself, to His Word, and to His will.
For Calvin, piety is comprehensive, having theological, ecclesiological, and practical dimensions. Theologically, piety can only be realized through union and communion with Christ and participation in Him, for outside of Christ even the most religious person lives only for himself. Only in Christ can the pious live as willing servants of their Lord, faithful soldiers of their Commander, and obedient children of their Father.
Communion with Christ is always the result of Spirit-worked faith, which unites the believer to Christ by means of the Word, enabling the believer to receive Christ as He is clothed in the gospel and graciously offered by the Father. By faith, believers possess Christ and grow in Him. They receive from Christ by faith the "double grace" of justification and sanctification, which together offer the cleansing of imputed and actual purity.
Ecclesiologically, for Calvin, piety is nurtured in the church by the preached Word, the holy sacraments, and psalm-singing. Believers cultivate piety by the Spirit through the church's teaching ministry, progressing from spiritual infancy to adolescence to full maturity in Christ.
The preaching of the Word is our spiritual food and our medicine for spiritual health, Calvin says. With the Spirit's blessing, ministers are spiritual physicians who apply the Word to our souls as earthly physicians apply medicine to our bodies.
Calvin defines the sacraments as testimonies "of divine grace toward us, confirmed by an outward sign, with mutual attestation of our piety toward him." Being the visible Word, they are "exercises of piety." The sacraments strengthen our faith, make us grateful for God's abundant grace, and help us offer ourselves as living sacrifices to God.
Calvin viewed the Psalms as the canonical manual of piety. He writes, "There is no other book in which we are more perfectly taught the right manner of praising God, or in which we are more powerfully stirred up to the performance of this exercise of piety." With the Spirit's direction, psalm-singing tunes the hearts of believers for glory.
Practically, although Calvin viewed the church as the nursery of piety, he also emphasized the need for personal piety. For Calvin, such piety "is the beginning, middle, and end of Christian living." It involves numerous practical dimensions for daily Christian living, with a particular emphasis on heartfelt prayer, repentance, self-denial, cross-bearing, and obedience.
Calvin strove to live the life of pietas himself. Having tasted the goodness and grace of God in Jesus Christ, he pursued piety by seeking to know and to do God's will every day. His theology and ecclesiology worked themselves out in practical, heartfelt, Christ-centered piety—piety that ultimately profoundly affected and transformed the church, the community, and the world.