As the gospel of grace reverberates the great exchange from the cross of Christ, faith stands alone as its sole conduit. The very nature of the gospel, being “good news” and not “good law,” requires that a sinner’s status before God is put right by faith alone in Christ alone, with no admixture of self-merit. Building on this necessity, Paul masterfully supports the thesis of justification by faith alone through the examples of two most prominent figures in redemptive history. The mystery of Christ is newly revealed, yet it is not a novelty. The very intelligibility of the gospel derives from the Old Testament. But even more, the stress of this passage shines a brilliant light on the function of faith. Here, we see precisely how justification works. Here, the great exchange is supported and clarified. Here, Christ is magnified as sinners are counted righteous by faith alone.