I don't know that it was the overwhelming majority, but a majority large enough and powerful enough to force the issue. Wikipedia writes of the differences of opinion in the south thus: Southern fears of losing control of the federal government to antislavery forces, and northern fears that the slave power already controlled the government, brought the crisis to a head in the late 1850s. Sectional disagreements over the morality of slavery, the scope of democracy and the economic merits of free labor vs. slave plantations caused the Whig and "Know-Nothing" parties to collapse, and new ones to arise (the Free Soil Party in 1848, the Republicans in 1854, the Constitutional Union in 1860). In 1860, the last remaining national political party, the Democratic Party, split along sectional lines. ======================== That there were many who did not agree can be seen from the amount of help that was given to fleeing slaves eg The Underground Railroad. At its height in the years before the Civil War, " The diverse "conductors" on the railroad included free-born blacks, white abolitionists, former slaves (either escaped or manumitted), and Native Americans. Churches and religious denominations played key roles, especially the Religious Society of Friends (Quakers), Congregationalists, Wesleyans, and Reformed Presbyterians as well as breakaway sects of mainstream denominations such as branches of the Methodist church and American Baptists.

I believe that the answer to that question is yes. Slavery built the south. It made people rich fast. It made the average southern white man feel superior. It united whites on all levels. Southern whites like naxis were brainwashed that slavery and racial superiority was their god given right.