Perhaps the surest mark distinguishing true assurance from false . . . is its continuing imperfection: 'the faithful have not this assurance so perfect, but they are oft troubled with doubts and fears. . . . But they that have this false assurance are most confident and never have any doubts.'
An unfeigned grief for the want of faith . . . is a sign of faith; to see and feel in our selves the want of any grace pertaining to salvation and to be grieved, therefore, is the grace itself.
Though God's decrees are immutable and no man whom He has predestined to salvation can fail to attain it, the surest earthly sign of a saint is his uncertainty; and the surest sign of a damned soul is security.
God kindles a spark of faith in the heart that is a 'will and desire to believe'. But no sooner is faith kindled than a combat begins in which the soul must fight against and despair by 'fervent, constant, and earnest invocation for pardon.' This combat never ceases, but it eventually produces a feeling of 'assurance' and persuasion of mercy. Thereafter follows an 'evangelical sorrow' that is ' a grief for sin, because it is sin', and lastly God gives a soul 'grace to endeavor to obey His commandments by a new obedience.'
Even after one reaches the stage of assurance, doubts may continue. If they ceased, that would be a sign that one had never had faith go begin with, but had merely deluded oneself and had not really entered in the covenant of grace.
True assurance comes only after attendance on the preaching of the word, and only after a period of doubt and despair. The faithful can always remember a time when they had the spirit of bondage in themselves which wrought much fear, while whose with false assurance are never troubled with any fears or doubts this way. --excerpts and paraphrases from "Visible Saints" by Edmund S. Morgan