Well, of course, if you are making a principled pacifist-Christian argument against all war, one can easily respect that.
My Dad fought in the Pacific during WWII, but some of my other relatives were pacifists, and did alternate service, in hospitals, etc.
No dishonor or disrespect there, in matters of principles and conscience.
But if, on closer look, it turns out that your Christian principles only apply to Union troops, and not to Confederates, then we have a disagreement.
If you've bought into pro-Confederate propaganda, asserting an unprovoked "war of northern aggression", it may be that you never learned how the Confederacy provoked, started & formally declared war on the United States, while sending military aid to pro-Confederates fighting in Union States.
You may not know that, once it started, there was no possible way, short of Confederate unconditional surrender, to end both the war and slavery.
Finally, you should understand that the actual record of civilian deaths is quite small -- dozens or hundreds, not thousands or millions.
That tells me our ancestors on both sides were in a class not equaled by any other civil war in history.
My argument was from the Christian principles regulating Just War. Much of this can be found (is it still there?) in the UCMJ. Nor do I think Yankee soldiers were all depraved war dogs,and CSA'ers were all Marse Robert.
If, as you say the rate of civilian casualties was much power in the U.S. Civil War than in other civil was, then I give credit to soldiers and officers who were just.
Related: the mass die-off of black slaves--- hundreds of thousands of them --- as a (surely unintended) consequence of the Civil War and its aftermath.