"2b1. From eternal election: the objects of justification are God's elect; "Who shall lay anything to the charge of God's elect? it is God that justifies"; that is, the elect. Now if God's elect, as such, can have nothing laid to their charge; but are by God acquitted, discharged, and justified; and if they bore this character of elect from eternity, or were chosen in Christ before the world began; then they must be acquitted, discharged and justified so early, so as nothing could be laid to their charge: besides, by electing grace men were put into Christ, and were considered as in him before the foundation of the world; and if they were considered as in him, they must be considered as righteous or unrighteous; not surely as unrighteous, unjustified, and in a state of condemnation; for "there is no condemnation to them which are in Christ", (Romans 8:1) and therefore must be considered as righteous, and so justified: "Justified then we were, says Dr. Goodwin when first elected, though not in our own persons, yet in our Head, as he had our persons then given him, and we came to have a being and an interest in him."
2b2. Justification may well be considered as a branch of election; it is no other, as one expresses it, than setting apart the elect alone to be partakers of Christ's righteousness; and a setting apart Christ's righteousness for the elect only; it is mentioned along with election, as of the same date with it; "Wherein", that is, in the grace of God, particularly the electing grace of God, spoken of before, "he has made us accepted in the beloved" (Ephesians 1:6). What is this acceptance in Christ, but justification in him? and this is expressed as a past act, in the same language as other eternal things be in the context, he "has" blessed us, and he "has" chosen us, and "having" predestined us, so he has made us accepted; and, indeed, as Christ as always the beloved of God, and well pleasing to him; so all given to him, and in him, were beloved of God, well pleasing to him, and accepted with him, or justified in him from eternity.
2b3. Justification is one of those spiritual blessings with which the elect are blessed in Christ according to election-grace, before the foundation of the world (Ephesians 1:3,4). That justification is a spiritual blessing none will deny; and if the elect were blessed with all spiritual blessings, then with this; and if thus blessed according to election, or when elected, then before the foundation of the world: and this grace of justification must be no small part of that "grace which was given in Christ Jesus before the foundation of the world was" (2 Timothy 1:9). We may say, says Dr. Goodwin, of all spiritual blessings in Christ, what is said of Christ, that his goings forth are from everlasting—in Christ we were blessed with all spiritual blessings, (Ephesians 1:3) as we are blessed with all other, so with this also, that we were justified then in Christ!
2b4. Christ became a Surety for his people from everlasting; engaged to pay their debts, bear their sins, and make satisfaction for them; and was accepted of as such by God his Father, who thenceforward looked at him for payment and satisfaction, and looked at them as discharged, and so they were in his eternal mind; and it is a rule that will hold good, as Maccovius observes, "that as soon as one becomes a surety for another, the other is immediately freed, if the surety be accepted;" which is the case here and it is but a piece of common prudence, when a man has a bad debt, and has good security for it, to look not to the principal debtor, who will never be able to pay him, but to his good bondsman and surety, who is able; and so Dr. Goodwin observes, that God, in the everlasting transaction with Christ, "told him, as it were, that he would look for his debt and satisfaction of him, and that he did let the sinners go free; and so they are in this respect, justified from all eternity."
2b5. The everlasting transaction, the same excellent writer thinks, is imported in 2 Corinthians 5:19 . "God was in Christ reconciling the world unto himself, not imputing their trespasses unto them". And the very learned Witsius is of opinion, "that this act of God may be called, the general justification of the elect." And, indeed, since it was the determination of God, and the scheme and method he proposed to take in Christ for the reconciliation of the elect, not to impute their sins to them, but to his Son, their Surety; then seeing they are not imputed to them, but to him; and if reckoned and accounted to him, then not to them; and if charged to him, then they must be discharged from them, and so justified; and a non-imputation of sin to the elect, is no other than a justification of them; and thus the apostle strongly concludes the imputation of Christ's righteousness; which is the "formalis ratio", or the form of justification, from the non-imputation of sin, and the remission of it (Romans 4:6-8)."
- excerpt from John Gill's A Body of Doctrinal Divinity