I am reading an essay by Packer on assurance in Puritan thought. What I found there surprised me. It also explained the wording of the Westminster Confession when it says that “infallible assurance” is possible. I am hesitant to say anyone’s assurance is really “infallible” because the warning passages of Scripture make grievous self-deception an ever-present possibility. But I am open to learning more from my Puritan teachers. This paragraph explains that the Westminster Confession was not saying that “infallible assurance” is commonplace; quite the contrary, the Westminster divines would have thought it comparatively rare among believers.
It is evident that “assurance” to the Puritan was something quite other than the “assurance” commonly given to the convert of five minutes’ standing in the enquiry room. (“You believe that John 1:12 is true? You have ‘received Him’? Then you are a son of God.”) The Puritans would not have called mere assent to such an inference, assurance at all. Professions of faith must be tested before they may be trusted, even by those who make them, and assurance, to the Puritan, was in any case more than a bare human inference; it was a God-given conviction of one’s standing in grace, stamped on the mind and heart by the Spirit…. The young convert’s position is really this: As he believes and obeys, he will know a measure of peace and joy, for real believing at once brings real comfort…; he may think and hope, and with some warrant, that he is a child of God, but he cannot say, in the unqualified sense of John’s first Epistle, that he knows his sonship until the Spirit sets this certainty home on his heart. Till the Spirit does so, in the Puritan sense, at any rate, he lacks assurance; which, said the Puritans, seems to be the case of most Christian people (“The Witness of the Spirit: The Puritan Teaching,” The Puritan Papers, vol. 1, p. 21).