Justification, the reformers insisted, is by grace alone, through the work of Christ alone. It is received on the principle of faith alone. And all this is established by Scripture alone. By this they took a firm stand in terms of choices. If we envision a ballot with two columns, one side honoring God and the other side honoring human beings, they were marking the God-honoring side of the ballot in clear repudiation of the human-honoring side. Each motto sounded a challenge to the humanistic system of medieval Catholicism. The truth is that they still challenge all humanistic religion today -- whether found in Catholicism, Protestantism, or in other Christian groups or movements that see themselves as somehow distinct from both of those categories.
Solely Grace
Justification is by grace alone (sola gratia), the reformers said, and by that they checked the ballot under gift, not merit. It is by grace, not of debt. It is given, not earned. Paul explicitly affirms this truth at least two times. In Romans 4:4 he says, "Now to the one who works, wages are not considered to be a gift but what is owed." And in Romans 1 1:6 he repeats, "And if it is by grace, it is no longer on the basis of works. If it were, grace would no longer be grace."
At this point we have but two choices. Either God saves us because we deserve it (debt), or he saves us although we do not deserve it (grace). There is no middle ground. It is altogether deserved, or else it is altogether undeserved. It is finally a matter of grace or merit. There can be no compromise. The reformers therefore insisted on sola gratia -- solely by grace -- and, saying that, they took their stand with Paul.
Solely Christ
God created human beings to enjoy sweet fellowship with himself. But instead of obeying God, we have broken his laws, ignored his wishes, displeased him and sinned. We are part of a sinful race (Rom. 5:19), "by nature" subject to divine wrath (Eph. 2:3). We also are sinners personally (Rom. 3:23). As surely as human life is God's gift, just that surely the consequence of sin is death (Rom. 6:23). How can a just and merciful God pronounce sinners "not guilty" and treat them as if they have done exactly what he desired? If he shows mercy, he will not be just. If he does justice, he will not show mercy. Humanly speaking, grace seems an impossible dream.
God resolved this dilemma in the person of Jesus of Nazareth. God himself took on human nature and became a baby boy in the womb of the Virgin Mary. In Jesus, the offended came to the offenders. In a human body, created for that purpose, Jesus gave God the perfect human obedience he had always wanted but had never before received (Heb. 10:5-10). By doing that, Jesus showed God's law to be both great and glorious (Isaiah 42:21). In one of his last prayers, Jesus could say, "I have finished the work that you gave me to do" (John 17:4).
Jesus then offered that faithful life "for sin," in his body on the cross, fulfilling the Isaiah prophecy of one who would "make his life an offering for sin" (53:10). On the cross, Jesus both received and gave. Like a great lightning rod suspended between heaven and earth, Jesus received and absorbed into his own body and soul all the consequences of human sin -- consequences culminating in his death. At the same time, Jesus gave God the Father the only life ever lived in perfect loving obedience to him. Jesus could therefore shout from the cross, "it is finished!" and with the satisfaction of an accomplished work, die satisfied (John 19:30; Isa. 53:11). God's grace did not come cheap, although for its recipients it is absolutely free.
In the work that accomplished salvation, there is no such thing as "God's part" and "our part." For it was wholly God's work to reconcile, justify and redeem, and he did that in Jesus, once for all. Our work comes after God has finished his work, and it is totally a response to God's work -- of grateful obedience and praise. Not until we have accepted the "it is finished!" concerning Jesus' work are we ready to hear "It is beginning" concerning his own work. And God's saving work is what he did in Jesus, not something he does in us. It was outside of us, for us.
Solely Faith
Because the work that accomplished salvation and reconciled us to God was done solely in the representative life and death of Jesus, it is a finished work. Since it was done completely in Jesus Christ, outside of us and before we were even born, we cannot contribute anything to it. We can do nothing to make it more acceptable than it has already been declared to be by Christ's resurrection (Rom. 4:25). We can do nothing to make it more certain than it already is seen to be in Christ at God's right hand (Eph. 2:6). Because it is done, we cannot do it, whether by climbing as high as heaven or stooping as low as hell (Rom. 10:6-8). We can only confess that Jesus is Lord, and believe that God has raised him from the dead -- and God pronounces us "not guilty" and we are rescued from our guilty condition (Rom. 10:9, 10). Or we can refuse to believe and continue under judgment. We cannot achieve salvation. We can only receive it. It is not ours by trying but by trusting. That is what the slogan "solely faith" actually means.
Solely Scripture
All this we learn in Scripture alone, and the authority of Scripture is sufficient to teach us the gospel regardless of what any man or group of men may say. Justification is therefore sola scriptura, the reformers said, completing the string of gospel pearls. What they said was not original. It was but a well-phrased summary of a single text in Romans 3:21, 22. For there Paul makes these same four points about our justification or acquital before God. It is a righteousness, he says, which is (1) "of God" (sola gratia); (2) "by faith of Jesus Christ" (solo Christo); (3) "unto all and upon all them that believe" (sola fide), (4) "witnessed to by the law and the prophets (sola scriptura).