Not entirely.
The editors at the Charleston Mercury agreed. They had anticipated the threat that a Republican victory would pose when in early November they warned South Carolinians and the entire South that “[t]he issue before the country is the extinction of slavery.” “No man of common sense, who has observed the progress of events, and is not prepared to surrender the institution,” they charged,“can doubt that the time for action has come—now or never.” The newspaper editors, like most Southerners saw Lincoln’s election as lifting abolitionists to power, and like most southerners they understood, as they plainly stated, that “[t]he existence of slavery is at stake.”
“What Shall the South Carolina Legislature Do?,”The Charleston Mercury, November 3, 1860. Source
If not, why do you insist that the Charleston Mercury speaks for the thousands of Southern men who died in that war?
Why not let their own words speak for them in letters written back home. Why not let Robert E. Lee's words on why he chose to fight for the Confederacy be the reason he fought.
Why must you take an issue that was not black and white and force it to be exactly that?
Which it was in reality. However Lincoln didn't care for any equality for blacks as he stated several times. But the abolitionists were instrumental in getting Lincoln voted in. But in reality that isn't what the war was about. Just look at what the Union's battle cry was. It WASN'T "Free the Slaves".
More of your misdirection.
Your source did some very careful editing of the Charleston Mercury editorial.
This phrase was left out of the middle of the quote you gave: "...with the safety and independence of the South...".
That was the motivation, liberty.