This grand doctrine of Justification was proclaimed in its purity and clarity by the Reformers—Luther, Calvin, Zanchius, Peter Martyr, etc.; but it began to be corrupted in the seventeenth century by men who had only a very superficial knowledge of it, who taught that justification consisted merely in the removal of guilt or forgiveness of sins, excluding the positive admittance of man into God's judicial favour: in other words, they restricted justification unto deliverance from Hell, failing to declare that it also conveys a title unto Heaven. This error was perpetuated by John Wesley, and then by the Plymouth Brethren, who, denying that the righteousness of Christ is imputed to the believer, seek to find their title to eternal life in a union with Christ in His resurrection. Few today are clear upon the twofold content of Justification, because few today understand the nature of that righteousness which is imputed to all who believe.
...The “righteousness of Christ” which is imputed to the believer consists of that perfect obedience which He rendered unto the precepts of God's Law and that death which He died under the penalty of the law. It has been rightly said that, “There is the very same need of Christ's obeying the law in our stead, in order to the reward, as of His suffering the penalty of the law in our stead in order to our escaping the penalty; and the same reason why one should be accepted on our account as the other…To suppose that all Christ does in order to make atonement for us by suffering is to make Him our Saviour but in part. It is to rob Him of half His glory as a Saviour. For if so, all that He does is to deliver us from Hell; He does not purchase Heaven for us” (Jonathan Edwards). Should any one object to the idea of Christ “purchasing” Heaven for His people, he may at once be referred to Ephesians 1:14, where Heaven is expressly designated “the purchased possession.”
...It is not that God treats as righteous one who is not actually so (that would be a fiction), but that He actually constitutes the believer so, not by infusing a holy nature in his heart, but by reckoning the obedience of Christ to his account. Christ's obedience is legally transferred to him so that he is now rightly and justly regarded as righteous by the Divine Law. It is very far more than a naked pronouncement of righteousness upon one who is without any sufficient foundation for the judgment of God to declare him righteous. No, it is a positive and judicial act of God “whereby, on the consideration of the mediation of Christ, He makes an effectual grant and donation of a true, real, perfect righteousness, even that of Christ Himself unto all that do believe, and accounting it as theirs, on His own gracious act, both absolves them from sin, and granteth them right and title unto eternal life” (John Owen).
It now remains for us to point out the ground on which God acts in this counter-imputation of sin to Christ and righteousness to His people. That ground was the everlasting covenant. The objection that it is unjust the innocent should suffer in order that the guilty may escape loses all its force once the covenant-headship and responsibility of Christ is seen, and the covenant-oneness with Him of those whose sins He bore. There could have been no such thing as a vicarious sacrifice unless there had been some union between Christ and those for whom He died, and that relation of union must have subsisted before He died, yea, before our sins were imputed to Him. Christ undertook to make full satisfaction to the law for His people because He sustained to them the relation of a surety. But what justified His acting as their surety? He stood as their Surety because He was their substitute: He acted on their behalf, because He stood in their room. But what justified the substitution?
No satisfactory answer can be given to the last question until the grand doctrine of everlasting covenant-oneness comes into view: that is the great underlying relation. The federal oneness between the Redeemer and the redeemed, the choosing of them in Christ before the foundation of the world (Eph. 1:4), by which a legal union was established between Him and them, is that which alone accounts for and justifies all else. “For both He that sanctifieth and they who are sanctified are all of one: for which cause He is not ashamed to call them brethren” (Heb. 2:11). As the Covenant-Head of His people, Christ was so related to them that their responsibilities necessarily became His, and we are so related to Him that His merits necessarily become ours. Thus, as we said in an earlier chapter, three words give us the key to and sum up the whole transaction: substitution, identification, imputation—all of which rest upon covenant-oneness. Christ was substituted for us, because He is one with us—identified with us, and we with Him. Thus God dealt with us as occupying Christ's place of worthiness and acceptance. May the Holy Spirit grant both writer and reader such an heart-apprehension of this wondrous and blessed truth, that overflowing gratitude may move us unto fuller devotedness unto Him who loved us and gave Himself for us. A.W. Pink