One of the most important and least known facts about the battle to abolish the slave trade in Britain two hundred years ago is that it was sustained by a passion for the doctrine of justification by faith alone. William Wilberforce was a spiritually exuberant and doctrinally rigorous evangelical. He battled tirelessly in Parliament for the outlawing of the British slave trade. It was doctrine that nourished the joy that sustained the battle that ended the vicious trade.

The key to understanding Wilberforce is to read his own book, A Practical View of Christianity. There he argued that the fatal habit of his day was to separate Christian morals from Christian doctrines. His conviction was that there is “perfect harmony between the leading doctrines and the practical precepts of Christianity.” He had seen the devastating effects of denying this: “The peculiar doctrines of Christianity went more and more out of sight, and...the moral system itself also began to wither and decay, being robbed of that which should have supplied it with life and nutriment.” But Wilberforce knew that “the whole superstructure of Christian morals is grounded on their deep and ample basis.”

This “ample basis” and these “peculiar doctrines” that sustained Wilberforce in the battle against the slave trade were the doctrines of: human depravity, divine judgment, the substitutionary work of Christ on the cross, justification by faith alone, regeneration by the Holy Spirit, and the practical necessity of fruit in a life devoted to good deeds. Wilberforce was not a political pragmatist. He was a radically God-centered, Christian politician. And his zeal for Christ, rooted in these “peculiar doctrines,” was the strength that sustained him in the battle.

At the center of these essential “gigantic truths” was (and is) justification by faith alone. The indomitable joy that perseveres in the battle for justice is grounded in the experience of Jesus Christ as our righteousness. “If we would...rejoice,” Wilberforce said, “as triumphantly as the first Christians did; we must learn, like them to repose our entire trust in [Christ] and to adopt the language of the apostle, ‘God forbid that I should glory, save in the cross of Jesus Christ,’ ‘who of God is made unto us wisdom and righteousness, and sanctification, and redemption.’”

In other words, the doctrine of justification is essential to right living—and that includes political living. Astonishingly, Wilberforce said that the spiritual and practical errors of his day that gave strength to the slave trade were owing to the failure to experience the truth of this doctrine:

They consider not that Christianity is a scheme “for justifying the ungodly” by Christ’s dying for them “when yet sinners”—a scheme “for reconciling us to God”—when enemies; and for making the fruits of holiness the effects, not the cause, of our being justified and reconciled.

This was why he wrote A Practical View of Christianity. The “bulk” of Christians in his day, he observed, were “nominal”—that is, they pursued morality without first relying utterly on the free gift of justification by grace alone through faith alone on the basis of Christ alone. They got things backward: first they strived for moral uplift, then appealed to God for approval. That is not the Christian gospel. And it will not transform a nation. It would not sustain a politician through eleven Parliamentary defeats over twenty years of vitriolic opposition.

The battle for abolition was sustained by getting the gospel right: “The true Christian . . . knows . . . that this holiness is not to precede his reconciliation to God, and be its cause; but to follow it, and be its effect. That, in short, it is by faith in Christ only that he is to be justified in the sight of God.” When Wilberforce put things in this order, he found invincible strength and courage to stand for the justice of abolition.

On this month’s two-hundredth anniversary of the abolition of the British slave trade, may Jesus Christ, the righteousness one, receive the credit he is due in the life of William Wilberforce.