This is a “prophetic” word from Calvin out of the Institutes related to the postmodern sensibilities of Western Christianity. I’m not implying Calvin was speaking directly against postmodernism itself as a formal philosophy, as it had not yet been articulated, but this certainly does speak against its core tenets asserted today, to be sure. And I would say that ultimately, postmodernism, within the setting of Christianity, leaves a person without certainty that they will be accepted before God, which is exactly what Calvin explains in this section. The reason for this is because if you have no certainty and a house built on solid rock, ultimately, you will try and pick up the slack of uncertainty through your own deeds, works and effort in order to please God, which oddly enough, is what we see happening with many (though not all) postmoderns in the focus of various ministry focal points (i.e. deeds versus creeds).
“We add, that it (faith) is sure and firm, the better to express strength and constancy of persuasion. For as faith is not contented with a dubious and fickle opinion, so neither is it contented with an obscure and ill-defined conception. The certainty which it requires must be full and decisive, as is usual in regard to matters ascertained and proved. So deeply rooted in our hearts is unbelief, so prone are we to it, that while all confess with the lips that God is faithful, no man ever believes it without an arduous struggle. Especially when brought to the test, we by our wavering betray the vice which lurked within. Nor is it without cause that the Holy Spirit bears such distinguished testimony to the authority of God, in order that it may cure the disease of which I have spoken, and induce us to give full credit to the divine promises: “The words of the Lord” (says David, Ps. 12: 6) “are pure words, as silver tried in a furnace of earth purified seven times:” “The word of the Lord is tried: he is a buckler to all those that trust in him,” (Ps. 18: 30.) And Solomon declares the same thing almost in the same words, “Every word of God is pure,” (Prov. 30: 5.)
But further quotation is superfluous, as the 119th Psalm is almost wholly occupied with this subject. Certainly, whenever God thus recommends his word, he indirectly rebukes our unbelief, the purport of all that is said being to eradicate perverse doubt from our hearts. There are very many also who form such an idea of the divine mercy as yields them very little comfort. For they are harassed by miserable anxiety while they doubt whether God will be merciful to them. They think, indeed, that they are most fully persuaded of the divine mercy, but they confine it within too narrow limits. The idea they entertain is, that this mercy is great and abundant, is shed upon many, is offered and ready to be bestowed upon all; but that it is uncertain whether it will reach to them individually, or rather whether they can reach to it. Thus their knowledge stopping short leaves them only mid-way; not so much confirming and tranquilizing the mind as harassing it with doubt and disquietude. Very different is that feeling of full assurance (“pleroforia”) which the Scriptures uniformly attribute to faith – an assurance which leaves no doubt that the goodness of God is clearly offered to us. This assurance we cannot have without truly perceiving its sweetness, and experiencing it in ourselves. Hence from faith the Apostle deduces confidence, and from confidence boldness. His words are, “In whom (Christ) we have boldness and access with confidence by the faith of him,” (Eph. 3: 12:) thus undoubtedly showing that our faith is not true unless it enables us to appear calmly in the presence of God. Such boldness springs only from confidence in the divine favor and salvation. So true is this, that the term faith is often used as equivalent to confidence.”