The doctrine of justification by faith alone is a bonfire lit in the darkness, and the Reformation proved Europe was desperate for its light. Emerging from the spiritual darkness of the Middle Ages, the Protestant Reformation brought back this essential truth, proclaiming: Post Tenebras Lux, “After darkness, light!” This guiding principle of the Reformation was inspired by verses such as Romans 3:28, “we hold that one is justified by faith apart from works of the law.”
The Heart of the Reformation
Justification by faith alone stands as the crown jewel of the Reformation. Why is this doctrine still so vital today? Why must we guard it fiercely? Martin Luther emphasized that we are justified by faith, apart from works. He warned:
“Nothing in this article can be conceded or given up…On this article stands all that we teach and practice against the pope, the devil, and the world. Therefore, we must be quite certain and have no doubt about it. Otherwise, everything is lost.”[1]
Martin Luther The Smalcald Articles, Preface 2
Luther understood this doctrine to be the foundation upon which all true theology rests. Likewise, John Calvin described justification as “the main hinge on which religion turns.”[2] Calvin’s warning highlights that without this doctrine, the Christian faith dissolves into dust.
Echoing this, English Puritan Thomas Watson compared errors concerning justification to cracks in the foundation of a building. He said:
“Justification by Christ is a spring of the water of life, and to have the poison of corrupt doctrine cast into this spring is damnable.”[3]
Thomas Watson Select Works
Today, the need to guard this truth is as important as ever. In an age where moralism and works-based theology have crept into Protestant teaching, the message of justification by faith alone remains a critical bulwark against distortions of the gospel.
The Judaizer Error: Then and Now
If the stakes are so high, why do many modern preachers attempt to snuff out the gospel light of the Reformation by blending faith with works as a condition for justification? This is just a modern version of the error the Judaizers made in Paul’s day. They blended faith and works, teaching that Gentile Christians needed both faith and adherence to the Mosaic law (circumcision) to be justified (Acts 15:5). Paul condemned this as false teaching, warning:
“You are severed from Christ, you who would be justified by the law; you have fallen away from grace” (Galatians 4:5).
Reformed theologian Francis Turretin said that “this is the very thing which Paul opposes against: faith mingled with works so that justification might be partly ascribed to faith and party to works” (Institutes 2.677).
In a similar way, some today blend works (moral performances) with faith, creating a subtle but dangerous distortion of the gospel. Commenting on the Judaizer error, J. Gresham Machen wrote:
“Paul saw very clearly that the difference between the Judaizers and himself was the difference between two entirely distinct types of religion; it was the difference between a religion of merit and a religion of grace. If Christ provides only a part of our salvation, leaving us to provide the rest, then we are still hopeless under the load of sin.[4]
J. Gresham Machen Christianity and Liberalism
Machen’s words remind us that mixing merit with grace, whether in Paul’s day or ours, creates a false gospel that leaves people in spiritual peril.
The moment we try to contribute to our justification with the intent to earn salvation, we deny the sufficiency of Christ’s finished work.
Justification by Faith Alone: The Gospel’s Core
For Reformed Christians, justification by faith alone (sola fide) is the heart of the gospel. Through faith, we receive the righteousness of Christ and forgiveness for our sins. The Heidelberg Catechism (Q.60) beautifully summarizes this:
“Even though my conscience accuses me of having grievously sinned against all God’s commandments, of never having kept any of them, and of still being inclined toward all evil, nevertheless, without any merit of my own, out of sheer grace, God grants and credits to me the perfect satisfaction, righteousness, and holiness of Christ, as if I had never sinned.”
Faith is a gift from God (Ephesians 2:8), and even our ability to believe is a result of His grace. Our good works, even those that arise from faith, play no part in our justification.
Just as Abraham’s faith in Christ was counted as righteousness (Romans 4:3), so too is ours. The gospel isn’t “be obedient and do good works,” but rather, “to the one who does not work but believes in Him who justifies the ungodly, his faith is counted as righteousness” (Romans 4:5).
Every religion outside of Christianity promotes salvation through works. Why would we ever trade the gospel for that? Who could ever do enough good works? Protecting the purity of sola fide is just as important today as it was during the Reformation.
The Council of Trent: A Sobering Warning
Adding our obedience to justification puts us in dangerous waters. Unfortunately, many in the Protestant world recoil from justification by faith alone and instead focus on making our works count toward salvation. It is important to remember that the Council of Trent, the Roman Catholic response to the Reformation, condemned the idea of justification by faith alone, declaring: “If anyone says that the sinner is justified by faith alone…let him be anathema” (Canon 9).
Sadly, the errors from Trent have crept into parts of the Protestant world. Mixing faith with works, no matter how well-intentioned, can create confusion about salvation and foster insecurity in believers. This confusion can lead to a belief that salvation is earned rather than freely given by grace. We must remain vigilant in protecting the purity of sola fide, ensuring it remains at the forefront of our Reformed faith, as it is the foundation upon which our hope rests.
Concluding Thoughts: Faith and Works
Someone will object: don’t Christians need to be obedient to be justified? While good works naturally follow faith, they play no part in our justification.
Calvin warned that blending faith and works means losing the gospel, saying:
“Righteousness according to grace is owed to faith. Therefore, it does not arise from the merits of works. Farewell, then, to the dream of those who think up a righteousness flowing together out of faith and works.[5]
Good works demonstrate that our faith is alive, but our obedience does not earn us a ticket to heaven. Justification (being declared righteous before God) comes by faith alone. Works are the fruit of justification, never its root. That distinction is the difference between a gospel that frees and a gospel that crushes.
