It would be foolish to claim slavery was not a causal factor in leading to The Civil War." probably even the "Final Cause" to us older language. But it was not the only cause or even a major cause.
Each and every discussion on slavery assumes it was an evil that is the basic premise. A moral judgment. The Bible never condemns slavery which fact is sometimes commented on.
Actually, it does. "Manstealing" is forbidden. In fact, it was a capital offense.
"And he that stealeth a man, and selleth him, or if he be found in his hand, he shall surely be put to death." -- Exodus 21:16
And clearly, slavery thoroughly violates the Golden Rule.
"[W]hatsoever ye would that men should do to you, do ye even so to them: for this is the law and the prophets." - Matthew 7:12
As Lincoln said, "Whenever I hear any one arguing for slavery I feel a strong impulse to see it tried on him personally."