Assurance as the Essence of Faith: Calvin vs. the Confession?

In 1995, I took a doctoral seminar class with Dr. Richard Gaffin in historical theology. Like the other students, I had to present my term paper in class. With great trepidation, I delivered my work on John Calvin’s position on saving faith and its connection to assurance. His definition of saving faith in the Institutes seemed clear enough: “A firm and certain knowledge of God’s benevolence toward us, founded upon the truth of the freely given promise in Christ, both revealed to our minds and sealed upon our hearts through the Holy Spirit” (3.2.7).  In short, he believed that assurance was of the essence of faith.
Based on my reading of the Westminster Confession of Faith concerning “Of Assurance of Grace and Salvation,” I argued that Calvin would have disagreed with the following: “This infallible assurance doth not so belong to the essence of faith, but that a true believer may wait long, and conflict with many difficulties before he be partaker of it” (WCF 18.3). Clearly, the Confession taught that assurance was not of the essence of faith. Or so I thought. 
New to the Reformed faith, I lacked awareness of the historical debate on this topic. For example, the 18th-century Marrow Controversy (over the free offer of Christ) in the Church of Scotland dealt with this issue to some extent. Both sides claimed faithfulness to the Westminster Confession. The Marrow Men contended that they and the Confession were consistent with Calvin on assurance as the essence of faith whereas their opponents believed that the Westminster divines departed from him. The latter is what I maintained, namely, that the Confession corrected Calvin. Eventually, I realized that my reading of both Calvin and the Confession was both superficial and erroneous.
First, Calvin’s affirmation that assurance was of the essence of faith was not a denial that one’s sense of assurance could not falter. He speaks of this very sense (or lack thereof) in the same chapter where he defines faith: “[F]aith is tossed about by various doubts, so that the minds of the godly are rarely at peace — at least they do not always enjoy a peaceful state” (3.2.37). True faith is an assured conviction embracing Christ, but those who believe on Christ may struggle with their sense of assurance. In the end, however much the believer’s faith is “vexed and troubled,” it overcomes and “never allows itself to be deprived of assurance of divine mercy” (3.2.21).
Second, the Confession states that assurance “does not so belong to the essence of faith,” that the “believer may wait long” and struggle much in receiving it. Notice, this statement implies that in some regard assurance is an essential aspect of faith. We get a better understanding of this in the Confession when it claims that the primary acts of saving faith are “accepting, receiving, and resting upon Christ alone” (14.2). Faith comes to Jesus saying, “I accept, receive, and rest upon you as MY savior.”
In response to the eighth query (on assurance as the essence of faith) of twelve from the General Assembly (1721) regarding the supposed errors of Marrow brethren, the latter cited Puritan John Rogers who calls faith “a particular persuasion of my heart, that Christ Jesus is mine.” For Rogers, faith moves beyond believing Jesus saves sinners to Jesus saved me a sinner. It is a “persuasion of the heart” that “whatsoever Christ did for the Redemption of mankind, he did it for me.” (Rogers, The Doctrine of Faith, 1627, p. 23) 
In the end, the Confession confirmed such a position though with different language. It affirmed assurance in some sense as an essential aspect of faith but not to the point that the believer’s sense of it cannot experience ebb and flow. Calvin would have agreed.
By way of application, we know that believers enjoy (or not) assurance on different levels. We also realize that some in the church “vainly deceive themselves with false hopes” of their interest in Christ (WCF 18.1).  Pastors must approach these different people with wisdom and sensitivity. The hope for all remains the same – seeking the Giver of assurance, Christ Jesus, beyond any quest for the gift of such that he gives. Still, we may truly pursue assurance founded on the promises of God, the evidences of grace, and the witness of the Spirit (WCF 18.2). Every believer, “enabled by the Spirit” may “know the things which are freely given” by God in Christ (WCF 18.3). Without extraordinary measures, every child of God can say (with Fanny Crosby), “Blessed assurance, Jesus is Mine.”
Bob McKelvey