In relationship to the biblical doctrine of reprobation, John Calvin writes:
I know that to attribute faith to the reprobate seems hard to some, when Paul declares it the result of election. Yet this difficulty is easily solved. For though on those predestined to salvation receive the light of faith and truly feel the power of the gospel, yet experience shows that the reprobate are sometimes affected by almost the same feeling as the elect, so that even in their own judgment they do not in any way differ from the elect [cf. Acts 13:48]. Therefore it is not at all absurd that the apostle should attribute to them a taste of the heavenly gifts [Heb. 6:4-6] – and Christ, faith for a time [Luke 8:13]; not because they firmly grasp the force of spiritual grace and the sure light of faith, but because the Lord, to render them more convicted and inexcusable, steals into their minds to the extent that his goodness may be tasted without the Spirit of adoption. Suppose someone objects that then nothing more remains to believers to assure themselves of their adoption. I reply: although there is a great likeness and affinity between God's elect and those who are given a transitory faith, yet only in the elect does that confidence flourish which Paul extols, that they loudly proclaim Abba, Father [Gal. 4:6; cf. Rom. 8:15]. Therefore, as God regenerates only the elect with incorruptible seed forever [I Peter 1:23] so that the seed of life sown in their hearts may never perish, thus he firmly seals the gift of his adoption in them that it may be steady and sure. But this does not at all hinder that lower working of the Spirit from taking its course even in the reprobate ... Besides this, the reprobate never receive anything but a confused awareness of grace, so that they grasp a shadow rather than the firm body of it. For the Spirit, strictly speaking, seals forgiveness of sins in the elect alone, so that they apply it by special faith to their own use. Yet the reprobate are justly said to believe that God is merciful toward them, for they receive the gift of reconciliation, although confusedly and not distinctly enough. Not that they are partakers of the same faith or regeneration with the children of God, but because they seem under a cloak of hypocrisy, to have a beginning of faith in common with the latter. And I do not deny that God illumines their minds enough for them to recognize his grace; but he so distinguishes that awareness from the exclusive testimony he gives to his elect that they do not attain the full effect and fruition thereof. He does not show himself merciful to them, to the extent of truly snatching them from death and receiving them into his keeping; but only manifests to them his mercy for the time begin. Only his elect does he account worthy of receiving the living root of faith so that they may endure to the end [Matt. 24:13]. Thus is that objection answered: if God truly shows his grace, this fact is forever established. For nothing prevents God from illumining some with a momentary awareness of his grace, which after vanishes." (III.2.11, pp 555-556).