Any good historian will tell you that it is impossible to completely understand a past event from a modern perspective.
No matter how we try to avoid it, modern views and prejudices will always imprint themselves on how we view the past.
That said, it is impossible to point to any single thing as "the driving force" behind the American Civil War.
It was the culmination of a disease with many symptoms.
If the objective of the war from the Union viewpoint was to end slavery, why would they have gone out of their way to ensure the slave-owning rights of the three slave states that stayed in the Union, and why would the Congress have approved the admission of a new slave state in 1863 (West Virginia)?
The truth is that slavery did not become an issue in the conflict until it was made one by the Union propaganda machine after the battle of Antietam.
The war was initiated to restore the Union and to restore the vast amount of national income that taxes on imports and exports.
Lincoln made mention numerous times before and after his election that he had no desire or intention to affect slavery in any way.
Speaking as a descendant of many soldiers on both sides of the war, that flag truly belongs to the hundreds of thousands of men, more than nine out of 10 of which were not slaveholders, who died beneath it to defend their homes against the Union invasion.
Personally I avoid use of the battle flag in display because of the horrid abuses of it committed by such groups as the KKK, preferring to fly the Stars and Bars on appropriate anniversaries and events.
However, those men are considered by act of Congress to be American veterans and are entitled to, at the very least, the honor of having the flag they died beneath fly over their cemeteries and be flown to honor their memory and their sacrifice.
This goes hand-in-hand with my anti-reparations view.
The debt owed from any cause or result of that war was, in my opinion, paid over five years with the blood of 700,000 American dead.