While, true, slavery was a key component of the Civil War, it was hardly the only one.
Name one great nation in world history that wasn't built on the backs of slavery. And I use "great" as meaning successful and powerful, not morally superior. A nation could not begin without it because there was no economy to build from. Free labor is the only dependable currency a young country could build itself upon.
Now, the ugly part of this truth is how American whites had convinced themselves that African "savages" were inferior, both intellectually and morally, thereby making the practice "acceptable" in many of their minds. This has repeated itself throughout history. The Romans did it. The Germans saw the Jews this way. Virtually every nation in world history had a targetted race or ethnicity. Even today, many Muslims see infidels in this same manner without apology. Look at Darfur.
It is a mistake to take today's views and try and supplant them into 1850, just a few decades after America was born and much was uncertain. Much of the South thought itself destined to break away from that union in the very early goings. (Iraq is in that condition right now; it takes considerable time.)
There was a vast economic disconnect from the North during those times that had nothing to do with slavery. It was similar to what you might see today between New York City and Omaha. Two completely different worlds. Totally different lifestyles. Different markets and economies entirely. A different set of values and priorities. Except in the years leading up to the Civil War, there wasn't a framework of a nation solidly in place as today.
That divide is still there. America is a conglomerate of very different people and values, and as natural migration to like-minded people continues to occur, there is a tangible divide that is deepening by the day. Though our nation is much more firmly established, talk of secession is constant and somewhat real. That will continue to deepen.
Of course, Americans are so fat, lazy, and stupid, they think such a thing could never happen again. They don't understand that this is still a very young nation, and every world power before us has eventually divided and crumbled, and we will one day, too, sooner or later.