Religious moral grounds is the reason the North opposed slavery.
Economic grounds is the reason the South required slavery.
Do not apply today's politics to the world 150+ years ago.
Churches were the center of social and intellectual life in the south. That was where people congregated, where they learned about the world and their place in it, and where they received moral guidance. The clergy comprised the community’s cultural leaders and educators and carried tremendous influence with slaveholders and non-slaveholders alike.
Southern clergy defended the morality of slavery through an elaborate scriptural defense built on the infallibility of the Bible, which they held up as the universal and objective standard for moral issues. Religious messages from pulpit and from a growing religious press accounted in large part for the extreme, uncompromising, ideological atmosphere of the time.
What were their arguments? The Presbyterian theologian Robert Lewis Dabney reminded his fellow Southern clergymen that the Bible was the best way to explain slavery to the masses. “We must go before the nation with the Bible as the text, and ‘thus sayeth the lord’ as the answer,” he wrote. “We know that on the Bible argument the abolition party will be driven to unveil their true infidel tendencies. The Bible being bound to stand on our side, they have to come out and array themselves against the Bible.”
Reverend Furman of South Carolina insisted that the right to hold slaves was clearly sanctioned by the Holy Scriptures. He emphasized a practical side as well, warning that if Lincoln were elected, “every Negro in South Carolina and every other Southern state will be his own master; nay, more than that, will be the equal of every one of you. If you are tame enough to submit, abolition preachers will be at hand to consummate the marriage of your daughters to black husbands.”
The Biblical argument started with Noah’s curse on Ham, the father of Canaan, which was used to demonstrate that God had ordained slavery and had expressly applied it to Blacks. Commonly cited were passages in Leviticus that authorized the buying, selling, holding and bequeathing of slaves as property. Methodist Samuel Dunwody from South Carolina documented that Abraham, Jacob, Isaac, and Job owned slaves, arguing that “some of the most eminent of the Old Testament saints were slave holders.” The Methodist Quarterly Review noted further that “the teachings of the new testament in regard to bodily servitude accord with the old.” While slavery was not expressly sanctioned in the New Testament, Southern clergymen argued that the absence of condemnation signified approval. They cited Paul’s return of a runaway slave to his master as Biblical authority for the Fugitive Slave Act, which required the return of runaway slaves.
As Pastor Dunwody of South Carolina summed up the case: “Thus, God, as he is infinitely wise, just and holy, never could authorize the practice of a moral evil. But God has authorized the practice of slavery, not only by the bare permission of his Providence, but the express provision of his word. Therefore, slavery is not a moral evil.” Since the Bible was the source for moral authority, the case was closed. “Man may err,” said the southern theologian James Thornwell, “but God can never lie.”
The Southern Presbyterian of S.C observed that there was a “religious character to the present struggle. Anti-slavery is essentially infidel. It wars upon the Bible, on the Church of Christ, on the truth of God, on the souls of men.” A Georgia preacher denounced abolitionists as “diametrically opposed to the letter and spirit of the Bible, and as subversive of all sound morality, as the worst ravings of infidelity.” The prominent South Carolina Presbyterian theologian James Henley Thornwell did not mince his words. “The parties in the conflict are not merely abolitionists and slaveholders. They are atheists, socialists, communists, red republicans, Jacobins on the one side, and friends of order and regulated freedom on the other. In one word, the world is the battleground – Christianity and Atheism the combatants; and the progress of humanity at stake.”
During the 1850’s, pro-slavery arguments from the pulpit became especially strident. A preacher in Richmond exalted slavery as “the most blessed and beautiful form of social government known; the only one that solves the problem, how rich and poor may dwell together; a beneficent patriarchate.” The Central Presbyterian affirmed that slavery was “a relation essential to the existence of civilized society.” By 1860, Southern preachers felt comfortable advising their parishioners that “both Christianity and Slavery are from heaven; both are blessings to humanity; both are to be perpetuated to the end of time.”
By 1860, Southern churches were denouncing the North as decadent and sinful because it had turned from God and rejected the Bible. Since the North was sinful and degenerate, went their reasoning, the South must purify itself by seceding. As a South Carolina preacher noted on the eve of secession, “We cannot coalesce with men whose society will eventually corrupt our own, and bring down upon us the awful doom which awaits them.” The consequence was a pointedly religious bent to rising Southern nationalism. As the Southern Presbyterian wrote, “It would be a glorious sight to see this Southern Confederacy of ours stepping forth amid the nations of the world animated with a Christian spirit, guided by Christian principles, administered by Christian men, and adhering faithfully to Christian precepts,” ie., the slavery of fellow human beings.