Why Assurance is "Of" the Essence of Saving Faith
The relationship between faith and assurance has been debated since the Reformation. Calvin held that assurance is “of” the essence of saving faith, meaning that when anyone believes in Christ for everlasting life, they are simultaneously sure they have that life. Do people today even consider whether assurance is of the essence of saving faith? This subtle but crucial prepositional distinction carries significant theological implications for how we understand eternal life.
Significance of "Of"
When we say assurance is “of” the essence, we are making a precise theological statement about the inherent components of saving faith. The preposition “of” indicates an inseparable relationship while maintaining distinct elements within saving faith.
Consider how belief operates: When someone believes something, they are persuaded of its truth. The preposition “of” captures this relationship perfectly. One can be persuaded that the sky is blue due to observation or that George Washington was America’s first president from reading historical documents, but they do not decide to believe it. As Kendall stated, “I cannot decide to believe what I am not persuaded is true.”
Practical Implications
This prepositional distinction carries significant implications for how we understand salvation. The question is not whether someone can decide to believe with partial conviction, but whether partial conviction constitutes Biblical belief at all. When Jesus offered eternal life to the woman at the well, He didn’t suggest a gradual process of becoming convinced – He offered immediate assurance through a single sip of water without the need for further drinking.
The Puritanical separation of faith and assurance undercuts the Biblical concept of faith. If we believe Jesus’ promise of eternal life, assurance isn’t an additional step. It is inherently part “of” that belief.
Jesus repeatedly stated that He is the Christ and can grant eternal life. All we have to do is believe Him. When we have doubts, does it mean that Jesus cannot fulfill His promise of everlasting life, or is it more of a reflection on our frailties? If one has faith (saving) in both the gift and Giver, then they can be assured they have eternal life that can never be lost due to our eternal life being secured by Jesus.
Abraham
The biblical model consistently demonstrates this inseparable relationship. Romans 4:21-22 describes Abraham as being “fully convinced that God was able to do what he had promised. That is why his faith was “counted to him as righteousness.” The text does not separate his belief from his assurance. They are inherently connected. This exemplifies why assurance must be “of” the essence of saving faith rather than a separate component.
The distinction of assurance being “of” the essence of saving faith is not mere semantic wordplay. It represents a crucial theological truth that impacts both our understanding of salvation and our approach to evangelism. This understanding stands in stark contrast to those who would attempt to separate assurance from faith, thereby diminishing both concepts.

