While many who served in the Confederate Army did so not to defend slavery, but their homes, that does not change the fact that no matter how much its defenders try to sugarcoat the issue, the Confederate States of America came into existing for only one reason, to defend the institution of race-based slavery. While there certainly were other disputes between north and south, largely based on the different needs of a slave-based economy and one based on free men, those who declared independence in 1860 and 1861 did not suffer from the delusion that there was any other issue save slavery that caused them to attempt a revolution.
This. I find it incredibly ironic that Democrats are the first to complain about it when they were the party that supported slavery, segregation, and the Confederacy when they existed.