There is absolutely no doubt that the issue of slavery became the lightening rod for the secession of the Southern States. However, the South was in fact fighting to protect their Constitutional Rights, not to "protect the institution of slavery. In an effort to avert war, the second 13th amendment was passed in Washington by the house and senate, and signed by the vice president on March 2, 1861, that protected the institution of slavery. H R No. 80 was a joint resolution to amend the constitution of the United States which read:
Resolved by the Senate and the House of Representatives of The United States of America in congress assembled, that the following article be proposed to the Legislatures of the several States as an amendment to the Constitution of the United States; which when ratified by three fourths of said Legislatures, shall be valid to all intents and purposes as part of said Constitution, namely: Art. 13. No amendment shall be made to the Constitution which will authorize or give to Congress the power to abolish or interfere, within any State, with the domestic institutions thereof , including that of persons held to labor or service by the laws of said State.
Seven States had already left the Union before March 2, 1861, however, not even the passage of H.R. No. 80 which was passed primarily by representatives of Northern States, was enough to hold the nation together. If this War was fought over slavery there was no need to fight since the House and Senate passed H R No. 80. All the South had to do was sit back and wait for it to be ratified.
However, Lincoln and his supporters in the Radical Republicans, opted to go to war to resolve the issue once and for all. Of course, the Radical Republicans were generally staunch abolitionist. They supported the immediate emancipation of all of those held in bondage and the granting of full and equal rights for the Negroes. They also supported other such radical causes as “women's suffrage and trade unionism! These ideas were well outside mainstream opinion of the day.
So when a statement is posted regarding the CSA leadership "To them slavery was an accepted practice, they even thought of it as God-sanctioned. But the idea that a black man was equal to a white, was extremely controversial, and they did whatever it took to downplay anything that upset their moral world view. Armed black slaves fighting as men making their own free will choices tilted that world view, and the CSA leadership then in power made no bones about saying so openly in the press." it seems to be a blatant attempt to cast aspersions on the character of these men as if they were not as morally evolved as Northerners. Well, in fact, that view of Negroes was the opinion of most Americans in the middle of the 19th century, Southerners and Northerners!
Bear in mind, that at the time, the Underground Railroad ended in Canada for more reasons than just the Fugitive Slave Act. Some Northern so-called “Free States” had laws forbidding Free Negroes from taking up residence in the States without posting a “peace Bond”. Both Indiana (1816) and Illinois (1818) had abolished slavery by their constitutions. And both followed the policy of Ohio, of trying to prevent black immigration by passing laws requiring blacks who moved into the state to produce legal documents verifying that they were free, which was seldom ever issued, and posting a bond to guarantee their good behavior. The bond requirements ranged as high as $1,000, which was prohibitive for a black American in those days. Anti-immigration legislation passed in Illinois in 1819, 1829, and 1853. In Indiana, such laws were enacted in 1831 and 1852. Michigan Territory passed such a law in 1827; Iowa Territory passed one in 1839 and Iowa enacted another in 1851 after it became a state. Oregon Territory passed such a law in 1849. Blacks who violated the law faced punishments that included advertisement and sale at public auction (Illinois, 1853).
Prejudice and discrimination was common throughout the entire United States, not just in the South. The issue of slavery is a "Red Herring" that offers NO ONE the high ground!!