The fact is that a Republic is governed by a mutually agreed upon set of laws. Those laws can only be changed by an act of legislation and not by mob opinions and moralistic concerns. Otherwise we would have a Theoracy as our government, a Government run by the Church. A Republic form of Government may have laws which are based in morality but those laws are agreed upon by legislation of the governing body, not by any group of persons who determine in their reasoning that some practise is right or wrong. There are many present day examples which could be cited as being as repugnant or even more so to some people today as slavery was then to the abolishionist. For example the Pro-Choice and Pro-Life debates today are an excellant parallel to the slavery debate of 1860 the argument of Law vs Morality. The Pro-choice movvement repersenting the southerners and the present laws, the Pro-life movement repersenting the Abolishionist moral concerns.
Had Slavery been outlawed by legislation of the United States Congress with all states debating the issue prior to 1860 would the southern states have seceeded?
Had the slave owners been offered compensation for their property losses as prescribed by the 4th Amendment would the southern states have seceeded?
The fact is that the southern slave owners were in favor of an English style of emancipation of their slaves which would have abolished the practise in just a couple of decades. But both the idea of compensation and English emancipation were rejected by the Radical Republican and abolishionist of the day creating the impass where no reasonable Legislational solution or compromise could be reached. The idea in the south was .'So you free the slaves, what do you do with them then?' They owned no property, and had no skills to earn a living, and there was no welfare and unemployment for them to draw. The moralistic abolishionist never answered those questions. We see the results of that failure today when looking back in history on 140 years of reconstruction program failures.
The radical Abolishionist demanded only one solution, Uncompensated immediate emancipation, without examing the consequences or considering the welfare of the slaves after their sudden emancipation. That lead to the break down in the rule of laws which is the foundation of a Republic form of Government, and lead the southern states to believe that being an independent nation was the only way to save THEIR Constitutional protections and the Republic that their forefathers had left them.