The reason why we are justified is not because we have faith. The reason we have faith is because we are justified. Faith is given by God. It is created in us for the express purpose of believing and espousing the Lord Jesus Christ and the testimony of Christ set out in the gospel. The elect are justified in their federal head, the Lord Jesus Christ. And that justification is applied to the conscience of believers. And then the assurance of it is sealed up in our hearts when grace enables us to believe the testimony concerning Christ. Consider if you will, this justification must be absolute and righteousness must be perfect. I will say it again. Justification must be absolute and righteousness must be perfect, that is, full and entire. And faith is never perfect and if faith were the essence of our justification then justification would be imperfect and so our righteousness. Thus, we view justification from three aspects, we believe biblically: (1) as decreed by God before the world, (2) in the death and resurrection of Christ—Romans 4:25, “Raised for our justification,” or some say on account of our justification—and then (3) in the grace of faith. Once we believe the gospel and see how we are justified before God, justification is sealed up in us, but it took its rise in the eternal counsels of the almighty God. He decreed it before the world. He made provision for it. Christ the lamb slain before the world ever began. When our sins are put upon Christ, as soon as they are imputed to him, so soon may he impute righteousness unto us and declare justification.
--- Pastor Bill McDaniel
The Surety of a Better Testament
Jesus is called "the surety of a better testament." Heb.vii.22. By the better testament, it is evident, the holy apostle means the covenant of grace, into which the sacred Three most graciously entered before the foundation of the world was laid, and in which all things relating to the salvation of sinners, and the glory of each divine person and perfection in that stupendous work, were wisely and immutably determined in the infinite, eternal mind; for of the very same testament of which he is the mediator he is the surety, his surety-ship being a part of his Mediational office; but it is of the eternal covenant of grace that he is the mediator, Heb. viii. 6; therefore, of that covenant he is the surety. In that ancient and glorious compact, replete with wisdom and love, God the Father was in Christ reconciling the world of his elect unto himself; not imputing their trespasses unto them. Then it was that he laid help upon one that is mighty; "Jesus! Mighty to save!" It must; therefore, be for these that the last-named illustrious personage engaged his gracious word, to become the surety; for, without his surety ship, there could be neither reconciliation to God, nor help in him for any sinner on earth.
--- Job Hupton
"Say some, suppose this doctrine of Justification from Eternity is true, what use or service is it of to men?"
I answer; it is our indispensable duty to make diligent search after divine truths. We cannot be excused in slight inquiries into what God has revealed in this world by this vain pretense, that we are unable to conceive what advantage may arise to us from the discoveries we make of some truths contained therein. Again: this objection is a very unbecoming reflection on the infinite wisdom and goodness of God; for it supposes that He has revealed something that is not profitable to His people, which must be esteemed a foul imputation on the divine perfections: for it is not to be imagined that God would, or can, reveal any doctrine to men, which is not in itself advantageous to them, however they may abuse it; wherefore this objection deserves to be treated with contempt. Farther, this doctrine, in my opinion, stands and falls with the important truths of God's everlasting love to His people; their eternal election in Christ, and the eternal covenant of grace. That Christ loved and delighted in His people from everlasting, is evident from these words, "my delights were with the sons of men" (Pr. 8:31). When did Christ thus delight in His people? The answer is, "before the mountains were settled, before the hills were brought forth; while as yet the earth was not made, nor the fields, nor the highest part of the dust of the earth" (Pr. 8:24-26): that is to say, before the world was formed. And the Father then took the same delight in these persons. That they were chosen in Christ, cannot be disputed; and, as viewed in him, they were never objects of condemnation, but always of Justification. If there is an eternal covenant of grace, in which Christ as Surety engaged to pay their debts, by virtue of such, they really became His, and the persons of the elect were acquitted of them by God and Christ, and also were justified in their account: whence it appears that eternal Justification is of the same weight and use as these doctrines are, for it is inseparably connected with them.