AFAIK, not one of the Founders publicly stated that slavery was a positive good, all viewing it as a great evil, but one that couldn’t be eliminated at the moment without great risk to society and the Union. This is certainly true, by their own words, for Washington, Jefferson, Madison and others who owned slaves themselves.
In hindsight this refusal to boldly face the contradiction between their principle of equality and the practice of slavery was by far their greatest mistake. It would have been much easier to put in place a gradual system of emancipation in the late 18th or early 19th centuries, before the cotton gin made the institution wildly profitable and the South built its economy and society on it.
I hope you can comprehend the difference between recognizing that immediate full implementation of the principles of the Declaration is impractical and proclamation that those principles are obsolete and untrue. See the Cornerstone Speech and numerous other southern proclamations that the Founders had been mistaken. All men are NOT created equal. And to prove it we will spread slavery far and wide both in time and in space.
The root principle of the Declaration is that “all men are created equal.” By its very wording all the other principles grow out of this one. If you reject the foundation, as the CSA did, you are left with no solid base.
Either all men are equal or some are more equal than others. Once you start down the second road, on what basis do you draw the line on who is and is not equal?
In the words of a great man, some years before the War, “Our progress in degeneracy appears to me to be pretty rapid. As a nation we began by declaring that ‘all men are created equal.’ When the Know-Nothings get control, it will read ‘all men are created equal, except Negroes and foreigners and Catholics.’ When it comes to this, I shall prefer emigrating to some country where they make no pretense of loving liberty — to Russia, for instance, where despotism can be taken pure, and without the base alloy hypocrisy.”
Luckily the Know-Nothings never got control, and their spiritual brethren of the CSA were defeated.
Yes, but we both know that the Founders were not talking about slaves. One can try to construe it that way, but it doesn't work. And what makes you think the CSA rejected this principle? Because they had slaves? All the colonies had slaves when the Declaration was passed, were they rejecting the principle? Sure, most recognized slavery as an evil, but so did most Southerners. Most Southerners were in favor of gradual emancipation. For a long time the South had more abolition societies than the North. Many Southerners freed their slaves. Washington did. My great x5 grandpa did. Many others had no slaves at all, such as Generals Lee, A. P. Hill, J. Johnston, and J. E. B. Stuart. Do you think they were somehow fighting for slavery? Does that make logical sense to you?
Your attempt at trying to make the issue that 6% of the white population had slaves a reason why the South could not form a legitimate government is lame. Here is what Lincoln had to say about secession:
"Any people anywhere, being inclined and having the power, have the right to rise up and shake off the existing government and to form one that suits them better. Nor is this right confined to cases in which the people of an existing government may choose to exercise it. Any portion of such people that can, may make their own of such territory as they inhabit. More than this, a majority of any portion of such people may revolutionize, putting down a minority intermingling with or near them who oppose their movement. "
Lincoln on the floor of Congress, 13 January 1848 Congressional Globe, Appendix 1st Session 30th Congress, page 94
What was the Republican plan for emancipation in 1860?