Westminster Confession, Chapter XVIII
III. This infallible assurance [of salvation] does 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: yet, being enabled by the Spirit to know the things which are freely given him of God, he may, without extraordinary revelation in the right use of ordinary means, attain thereunto. And therefore it is the duty of every one to give all diligence to make his calling and election sure, that thereby his heart may be enlarged in peace and joy in the Holy Ghost, in love and thankfulness to God, and in strength and cheerfulness in the duties of obedience, the proper fruits of this assurance; so far is it from inclining men to looseness.
John Calvin, Institutes of the Christian Religion, (J. T. McNeill, ed., Louisville, KY: Westminster John Knox Press, 2011) III.ii.15-16.
Also, there are very many who so conceive God’s mercy that they receive almost no consolation from it. They are constrained with miserable anxiety at the same time as they are in doubt whether he will be merciful to them because they confine that very kindness of which they seem utterly persuaded within too narrow limits…But there is a far different feeling of full assurance that in the Scriptures is always attributed to faith. It is this which puts beyond doubt God’s goodness clearly manifested for us [Col. 2:2; 1 Thess. 1:5; cf. Heb. 6:11 and 10:22]. But that cannot happen without our truly feeling its sweetness and experiencing it in ourselves. For this reason, the apostle derives confidence from faith, and from confidence, in turn, boldness. For he states: “Through Christ we have boldness and access with confidence which is through faith in him” [Eph. 3:12 p., cf. Vg.]. By these words he obviously shows that there is no right faith except when we dare with tranquil hearts to stand in God’s sight. This boldness arises only out of a sure confidence in divine benevolence and salvation. This is so true that the word “faith” is very often used for confidence.
Here, indeed, is the chief hinge on which faith turns: that we do not regard the promises of mercy that God offers as true only outside ourselves, but not at all in us; rather that we make them ours by inwardly embracing them. Hence, at last is born that confidence which Paul elsewhere calls “peace” [Rom. 5:1]…Briefly, he alone is truly a believer who, convinced by a firm conviction that God is a kindly and well-disposed Father toward him, promises himself all things on the basis of his generosity; who, relying upon the promises of divine benevolence toward him, lays hold on an undoubted expectation of salvation.
I know many people (following Richard Muller et. al) will complain that I am trying to resurrect the dead caricature of ‘Calvin vs. the Calvinists’. But it seems patently obvious to me, just on a simple comparison of these two passages regarding the relation of assurance to faith, that there is a significant difference! The Calvinian emphasis on assurance as inextricably bound up with saving faith – in contrast with Westminster’s division of the two – is one of the reasons why Evangelical Calvinism distinguishes itself as evangelical – i.e. truly good news! – as opposed to classical or federal Calvinism of the Westminster variety.