The Puritan Thomas Watson lays down ‘four maxims or positions about justification.
1 That justification confers a real benefit upon the person justified. The acquitting and discharging of the debtor, by virtue of the satisfaction made by the surety, is a real benefit to the debtor. A robe of righteousness, and a crown of righteousness, are real benefits.
2 All believers are alike justified: justificatio non recipit magis et minus. Justification does not apply to some more than to others.! Though there are degrees in grace, yet not in justification; one is not justified more than another; the weakest believer is as perfectly justified as the strongest; Mary Magdalene is as much justified as the Virgin Mary. This may be a cordial to a weak believer. Though thou hast but a drachm of faith, thou art as truly justified as he who is of the highest stature in Christ.
3 Whomsoever God justifies, he sanctifies. ‘But ye are sanctified, but ye are justified.’ 1 Cor 6:11: The Papists calumniate Protestants; they report them to hold that men continuing in sin are justified; whereas all our Protestant writers affirm, that righteousness imputed, for justification, and righteousness inherent, for sanctification, must be inseparably united. Holiness indeed is not the cause of our justification, but it is the attendant; as the heat in the sun is not the cause of its light, but it is the attendant. It is absurd to imagine that God should justify a people, and they should still go on in sin. If God should justify a people and not sanctify them, he would justify a people whom he could not glorify. A holy God cannot lay a sinner in his bosom. The metal is first refined, before the king’s stamp is put upon it; so the soul is first refined with holiness, before God puts the royal stamp of justification upon it.
4 Justification is inamissibilis; it is a fixed permanent thing, it can never be lost. The Arminians hold an apostasy from justification; to-day justified, tomorrow unjustified; to-day a Peter, to-morrow a Judas; today a member of Christ, to-morrow a limb of Satan. This is a most uncomfortable doctrine. Justified persons may fall from degrees of grace, they may leave their first love, they may lose God’s favour for a time, but not lose their justification. If they are justified they are elected; and they can no more fall from their justification than from their election. If they are justified they have union with Christ, and can a member of Christ be broken off? If one justified person may fall away from Christ, all may; and so Christ would be a head without a body.’
(A Body of Divinity)