“Our justification is the direct result of our believing the gospel; our knowledge of our own justification comes from believing God’s promise of justification to everyone who believes these glad tidings. For there is not only the divine testimony, but there is the promise annexed to it, assuring eternal life to everyone who receives that testimony.There is first, then, a believed gospel, and then there is a believed promise. The latter is the “appropriation,” as it is called; which, after all, is nothing but the acceptance of the promise which is everywhere coupled with the gospel message. The believed gospel saves; but it is the believed promise that assures us of this salvation.
Yet, after all, faith is not our righteousness. It is accounted to us in order to (είς)righteousness (Romans 4:5), but not as righteousness; for in that case it would be awork like any other doing of man, and as such would be incompatible with the righteousness of the Son of God; the “righteousness which is by faith.” Faith connects us with the righteousness, and is therefore totally distinct from it. To confound the one with the other is to subvert the whole gospel of the grace of God. Our act of faith must ever be a separate thing from that which we believe.
God reckons the believing man as having done all righteousness, though he has not done any, and though his faith is not righteousness. In this sense it is that faith is counted to us for, or in order to, righteousness, and that we are “justified by faith.” Faith does not justify as a work, or as a moral act, or a piece of goodness, nor as a gift of the Spirit, but simply because it is the bond between us and the Substitute; a very slender bond in one sense, but strong as iron in another. The work of Christ for us is the object of faith; the Spirit’s work in us is that which produces this faith: it is out of the former, not of the latter, that our peace and justification come. Without the touch of the rod the water would not have gushed forth; yet it was the rock, and not the rod, that contained the water. – Horatius Bonar, The Everlasting Righteousness, Or, How Shall Man Be Just With God?