Keep on stretching like this and you're going to strain something. The Civil War was caused by religion? No. Slavery was an extension of racial inequality and those ideas are a lot older than Christ. Perhaps Christianity was used as an excuse, but it was not the root cause. An interpretation was the root cause, and that interpretation was born of the natural predication of human beings to fear that which they do not fully understand - like, for instance, Europeans (and later Americans) failing to understand African culture and simply labeling them savages.
Actually most of the racial bias that was perpetuated by later christianity developed after they discovered southern africa - indeed it was Jesuit priests who helped to propogate this bias through their missionary work.
The slavery of ancient times was of the sort that meant that respect for your slaves was given, and providing your slaves towed the line you were expected to treat them with dignity.
American slavery was based both upon the old european ideals of serfdom, mixed in with the racial prejudices of rennaisance christianity.