As Secretary of State William Seward said when the Emancipation Proclamation was issued: "We show our sympathy with slavery by emancipating slaves where we cannot reach them and holding them in bondage where we can set them free."
If it were a "righteous cause" for which they were fighting, why didn't they free their own slaves to demonstrate that this was indeed the cause for which they were fighting?
The actual cause for which they were fighting appears to be stopping those Southerners from trading with Europe without sending millions of dollars North to Washington DC and New York.
I know this is your oversimplified pet theory, which you tirelessly defend. However, the overwhelming evidence from the time period—in the form of correspondence from countless everyday Americans—illustrates the fact that ending slavery was indeed the "righteous cause". And perpetuating slavery was undeniably the "cause" of the South.
While there were doubtless economic and financial interests involved on all sides, claiming such factors as the primary "cause" for the fighting is simply not the consensus of Civil War historians, nor Americans in general. Your position remains that of a small minority...