Spin-off from the debate in the "Because, Trump" thread:
I strongly suspect if there had been a hint of religion in the causes of the American civil war, America would be no different right now
Given the extreme bloodshed of the ACW, had religion factored in, there would be two separate countries now. In the age of steam rail, canal boats, and efficient ships, people wouldn't have just stuck in place and endured.
However, I think you are badly off base in the usual European sense, that of conflating faith and religion in American culture. The worst overlap between religion and government here wasn't after the Revolution, or the ACW, it was during the 17th century when local governments at the behest of English governors required church (CoE, specifically) attendance in the mid-Atlantic colonies such as Virginia. Not surprisingly, the very concept of governmental secularity comes from Virginia (reinforced by the mess in Maryland after the Revolution).
There's a grandiose What If somewhere in there, though it would in fact take some effort to introduce a religious angle into domestic American conflict. Probably to the point of eliminating the Establishment Clause from the First Amendment.
There WAS some linkage. I remember listening to a Podcast about John Brown, and he was IIRC, regarded as something of a religious fanatic. The Harpers Ferry Incident clearly was very large step along the way towards the Civil War. But although he seemed to receive a lot of patronage from people with religious scruples whom were linked to slavery abolitionists I dont get the impression abolition was more more than a fringe issue. One that most churches in the US would perhaps, understandably for the time, have steered a wide berth around.
I just looked around a little, and I think a possible handle might be via George Whitfield's slavery advocacy and Methodism. If southerners had realized the use of linking government to a denomination justifying the institution during the revolutionary era, things might have looked differently. As it is, the Methodist Episcopals, Presbyterians and Baptists all split into Northern and Southern branches over the issue 1837-1845.
Wasn't a large segment of the abolitionist movement in the US and the UK vested in religious concepts?
How religious could it have been considering how deeply slavery is built into the Old Testament.
You can find a line for anything you want a religious backing for in the bible.
Slavery was baked into MOST cultures. It shows up in religion because most cultures had religion as one of the early structures for organizing their culture. It was a step forwards from the older step of just murdering all of the other members of the tribe you were in conflict for.
One need not look JUST at Christian doctrine for examples. Look also at any number of other pre-christian cultures and you find it there as well.
Christian abolitionists certainly believed God demanded they work to eliminate slavery. It may well be that their interpretation of the Bible disagreed with pro-slavery interpretations, but that does not invalidate their beliefs or work.
Some primers via Wikipedia: