Theodore Parker was far from a typical 19th-century preacher. A bold reformer and one of the most outspoken voices against slavery in pre–Civil War America, he challenged both church and society with his radical beliefs. While most ministers of his time urged enslaved Africans to accept their suffering in silence, Parker argued in his sermons and writings that they had a natural right to resist their oppression, even to kill their masters if that was the only way to gain their freedom.
Born in Lexington, Massachusetts, Parker was raised in a strict religious household. From an early age, he displayed an unshakable curiosity about religion, morality, and justice. He studied theology at Harvard Divinity School, where he began to challenge traditional Christian teachings, especially those that seemed to justify oppression. Parker’s sermons soon became famous not only for their intellectual depth but for their boldness. He preached a practical religion centered on human conscience, moral action, and the pursuit of truth rather than rigid dogma.
When the issue of slavery dominated national politics in the 1840s and 1850s, Parker took an uncompromising stand. To him, slavery was not only politically wrong but morally evil. He declared that a system built on the ownership, torture, and degradation of human beings could never be justified under God’s law. Unlike more cautious abolitionists, Parker believed that moral persuasion alone was not enough.
In 1841, he preached a sermon titled A Discourse on the Transient and Permanent in Christianity, which became one of the most controversial religious statements of the time. In it, he argued that true Christianity wasn’t found in the miracles or dogmas of the Church, but in the eternal truths of justice, love, and moral conscience.
That sermon came at a heavy cost. Most churches in Boston shut their doors to Theodore Parker, and many ministers publicly condemned him as a heretic. He was ostracized by much of the religious community, but he refused to give in. Instead, he started his own congregation, the Twenty-Eighth Congregational Society of Boston, where as many as 2,000 people would come to hear him preach.
Parker’s sermons were fiery and uncompromising. He called slavery “a curse upon the soul of the Republic” and believed that no nation could claim to be democratic while millions were enslaved. “We must give up democracy if we keep slavery,” he said, “or give up slavery if we keep democracy.”
When Congress passed the Fugitive Slave Act of 1850, a law that forced citizens in free states to help capture escaped slaves, Parker called it “a hateful statute of kidnappers.” He helped found the Boston Vigilance Committee, an underground network that hid and protected freedom seekers. His own home became a safe house for fugitives like William and Ellen Craft. For this, he was indicted but never convicted.
Theodore Parker was not just a man of words. He was one of the “Secret Six,” a small group of Northern abolitionists who secretly financed and supported John Brown’s plan to start an armed slave uprising in the South, believing it could spark a rebellion that would end slavery once and for all.
Although Parker was already ill and living in Europe when Brown attacked Harpers Ferry in October 1859, he followed the news closely and defended Brown even after his capture. Parker called him a martyr, writing, “The road to heaven is as short from the gallows as from a throne.”
After Brown’s execution, Parker wrote a bold letter from Rome titled John Brown’s Expedition Reviewed, which was later published in Boston. In it, he defended Brown’s actions and made one of the most radical moral arguments of his time.
Parker stated that anyone held in slavery had a natural right to kill anyone who tried to keep them enslaved. “A man held against his will as a slave,” he wrote, “has a natural right to kill every one and all who seek to prevent his enjoyment of liberty.” He compared this right to self-defense, arguing that if it is lawful to kill a murderer or a wild beast to save one’s life, then it must also be just for an enslaved person to destroy the master who denies them freedom.
He went even further, insisting that free people also had a moral duty to help enslaved people win their freedom, even if it required violence. To Parker, slavery was not just a social wrong but a war against humanity, and he believed that moral men were bound to fight back by any means necessary.
In his letter, Parker warned that uprisings like John Brown’s would continue for as long as slavery existed, because no amount of violence could silence the human desire for freedom.
Not long after writing those words, Parker’s health deteriorated rapidly. Tuberculosis had weakened him, and despite his determination, he could no longer continue his public work. Surrounded by a few close friends, he passed away on May 10, 1860, less than a year before the Civil War began, a conflict that would finally bring about the end of slavery he had long predicted.
He was buried in Florence’s English Cemetery. Years later, when abolitionist Frederick Douglass visited the city, he made a point of visiting Parker’s grave to pay tribute to the white preacher who had bravely defended the right of Black people to fight for their freedom.
Sources:
https://library.harvard.edu/collections/theodore-parker-papers
https://www.uuworld.org/articles/parker-radical-theologian
