Causes of the American Civil War
While there's no simple answer to this matter, we can say that slavery was the main issue in the American Civil War. This is what divided the country in two: North and South.
The most radical and influential abolitionists of the North were determined to stop slavery, and had no problem in going to war for it. Meanwhile, in the South, politicians believed that they had the right of owning slaves.
Therefore, the leaders of the North started convincing people that war was crucial or otherwise the South would secede and this would hurt democracy awfully. The South leaders persuaded their people that the North was after his culture and customs. The truth is that if slavery was abolished, the entire South economy would suffer deeply, because their system was based upon cotton and slavery.
However, slavery wasn't the only reason the war started. It also had to do with the possibility of a state leaving the Union and the continuation of antebellum southern way of life.