The pagan philosopher Plutarch writes that, regarding beliefs in God, we should avoid two extremes: atheism and superstition. The former abandons all ideas of God, whereas the latter holds false ideas of a malevolent deity.
In Book 3 Chapter 2 of the Institutes, Calvin provides a definition of the Christian faith, which is opposed to both atheism and superstition:
Faith is a firm and sure knowledge of the divine favor toward us, founded on the truth of a free promise in Christ, and revealed to our minds, and sealed on our hearts, by the Holy Spirit.
There are several points of doctrine here:
First, faith is not ignorant, but is founded on the revealed knowledge of God. No one can have faith unless God reveals Himself to him.
Second, faith is authored by the Triune God, the Father, the Son and the Holy Spirit.
Third, faith receives a precious promise from God, a promise fulfilled in Christ, and communicated to the believer through the Spirit.
Fourth, faith is not only consent of the intellect, but also obedience of the heart, to the work of the Spirit.
Fifth, faith is sure and steadfast, which anchors the soul in the presence of God.
While Calvin’s exposition of faith is biblically sound, it suffers a major defect as a definition: explaining one little understood entity, faith, with another less understood, God.
Regarding the crucial and practical question, (how) can an individual be sure that he has saving faith? Calvin doesn’t give a satisfactory answer. On the one hand, he expounds on the total depravity and deceitfulness of the heart, even the heart of a believer; on the other hand, he insists that a believer can be certain that the faith of his heart is genuine. This seems self-contradictory.
It is evident that certainty, that is, peace of conscience, is important to Calvin. Because of the total depravity of man, for the salvation of man to be certain, it must be the work of God alone from start to finish. However, this certainty is of God, not of man. The Lord knows those who are His and will be saved, it doesn’t follow that a man can be certain of his own salvation. Calvin rejects universal salvation, therefore he cannot derive the certainty of his salvation from God’s love for mankind; nor can certainty be derived from an intellectual knowledge of the doctrine of salvation–knowing what is just is not the same as being just; nor can certainty be derived from the feelings and motions of a depraved and deceitful heart. What then? To make the matter more perplexing, Calvin also points out that there are false believers (cf. The Parables in Matthew 13), who deceive others and themselves concerning the Christian faith, who believe themselves to be Christians but are not in truth. As it is written, “The heart is deceitful above all things, and desperately wicked; Who can know it?”
A man cannot be certain of his own salvation, unless God communicates His certainty and peace to the heart of the man. If God thus communicates Himself to man, man is no longer depraved, but godly.