As I read Peter Turchin’s book Ages of Discord and follow current events, it couldn’t be more clear to me that Avery Craven and James G. Randall were correct in their interpretation of the War Between the States. More recently, David Goldfield has resurrected the Blundering Generation thesis.
Slavery was not the cause of the War Between the States. The Second Great Awakening which injected religious fanaticism into American politics was the cause. It was this religious fanaticism that led to abolitionism which migrated into politics and polarized and dissolved the Union. Interestingly, Goldfield explains how the spirit of religious fanaticism quelled after Antietam and through the Reconstruction period. Materialist values became ascendant in the North and led to the Gilded Age.
Note: It is easier to see today now that we are living through a similar period in the historical cycle. Slavery doesn’t exist anymore, but look where we are now. Look how similar our times are to the 1850s.