The Reformation was, at its core, the recovery of the biblical doctrine that Scripture is the only final authority (sola Scriptura) for the Christian faith and the Christian life, that salvation is by divine favor alone (sola gratia), through faith alone (sola fide), and that all glory goes to God alone (soli Deo gloria). These are authentic, sixteenth-century doctrines and axioms, which the confessing Reformation churches still believe and still teach. The Reformation solas, however, are not well known or understood outside the confessional Protestant world. E.g., among evangelicals the Reformation doctrine of sola Scriptura is regularly misunderstood to mean that we read the bible by itself, in isolation from the church, in isolation from church history, and in isolation from the creeds and confessions. John Calvin called this doctrine nuda scriptura, bare scripture. This was not the Reformation approach to Scripture but it is the straw man often used by Romanist critics of sola Scriptura.
There are similar problems with the reception of sola gratia and sola fide. The contest between Rome and the Reformation was not over whether we are saved and justified by grace and faith but over whether we are justified by grace alone, through faith alone. The contest was over the definition of grace and faith. Rome defined grace as a substance, either divine or created. According to Rome, we are said to be infused with grace (a medicinal substance) with which we must cooperate sufficiently to be sanctified and made inherently righteous. By contrast, the Protestants taught (and confess today) that grace is God’s unconditional favor for helpless sinners. According to Rome, faith is not, as the Protestants say, knowledge (notitia), assent (assensus), and trust (fiducia) but trusting and obeying or faithfulness. According to Rome we are justified because we are sanctified. According to Rome, we are justified and saved by grace and cooperation with grace. The Reformation rejected that doctrine as the very thing that Paul opposed. Paul juxtaposed grace and works (Rom 11:6). The “cooperation” that Rome requires is the very thing that Paul condemned among the Galatians and to the Roman congregation. With Paul we say that we are “justified by faith apart from the works of the law.” Cooperation with grace is “the works of the law.” The Judaizers and rabbis whom Paul opposed taught grace and cooperation with grace.
According to Scripture and the Reformation confessions, faith is not our faithfulness. The object of faith is Christ and his righteousness for us. Faith apprehends Christ and his benefits. By divine favor alone, sinners are given new life and true faith. That faith lays hold of Christ, rests in Christ, trusts Christ for righteousness and salvation (justification, sanctification, and glorification). The power of faith is not faithfulness—that is the Roman doctrine faith formed by love. According to Scripture as understood in the Reformation churches, faith is formed by Christ. That is why faith is the alone instrument of justification and salvation, because Christ alone is our righteousness and he alone is our Savior. We say that to try to add to Christ’s work is to make him but half a Savior, which is, we confess, a blasphemy too gross even to utter.
Thus, the Reformation solas remain today as radical and offensive as they were in the 1520s when Luther first articulated them. To aid in the recovery of these essential biblical and Reformation doctrines here is the Heidelblog resource page on the solas.