“There is a double object in the promise, which relates to both the understanding and the will. As the promise is true, so it calls for an act of assent from the understanding; as it is good as well as true, so it calls for an act of the will to embrace it. Therefore, the person who knows the truth of the promise only intellectually, without clinging to it, does not believe savingly. That person no more receives benefit from the promise than a person who realizes food is nourishing but refuses to eat.
Justifying faith is not assurance. If it were, John might have spared himself the trouble of writing to “you that believe on the name of the Son of God, that ye might know that ye have eternal life,” (1 John 5:13). His readers might then have said, “We already do this. Is it not faith to believe that we are among those pardoned through Christ, and that we shall be saved through Him?” But this cannot be so. If faith were assurance, then a man’s sins would be pardoned before he believes, for surely he must be pardoned before he can know he is pardoned. The candle must be lighted before I can see it is lighted. The child must be born before I can be assured it is born. The object must be before the act.
Assurance is not faith itself, but rather the fruit of faith. Assurance is in faith as the flower is in the root. Faith, in time after much communion with God, acquaintance with the Word, and experience of His fellowship with the soul may flourish into assurance. But as the root truly lives before the flower appears, and continues after it and its beautiful petal are gone, so does true justifying faith live before assurance comes, and live on after it disappears. Assurance is like the sunflower, which opens with the day and shuts with the night. But faith is a plant that can grow in the shade, a grace that can find the way to heaven in a dark night. It “walketh in darkness,” and yet will “trust in the name of the Lord” (Isa. 50:10).” -William Gurnall