Not quite correct. Slavery was the wedge issue, a moral issue used by Northern Whig and Republican politicians to split the Democratic Party on sectional lines and to split off the agrarian Midwest from the agrarian South.
It dominated the decision on states coming into the union and the issue over which side, slave or free, would have dominance.
Partly true -- whether a new State permitted slavery was a pretty good indicator of which bloc in Congress it would adhere to. John Quincy Adams and the Federalist/Whig bloc kept Texas out of the Union for 10 years for that very reason.
If you look at virtually every conflict between north and south 40 years prior to the war it is slavery which is at the heart of the conflict.
That's incorrect. The Nullification Crisis of the 1830's was precipitated by regional bad feeling over the Tariff of Abominations of 1828. That crisis was all about money.
Fact is, without slavery there would never have been a civil war.
Without the Big Bang, there would never have been a Civil War, either. Slavery was a factor in the Civil War, which was nevertheless a leadership struggle and a battle among proud and ruthless men over political power and which States got to stick it to which other States. The triumph of Republicanism put the whole country on a timeclock and made its people thralls, in one way or another, to the private interests of the few, and the political power that rested on those interests.
Courtesy ping.
That is of course the view of southern apologists who can't accept that the south was fighting to preserve a way of life which at it's core was about slavery. Without slavery the southern culture would not have existed as it was and there would not have been the sectionalism that existed. Read primary source material from the time and the issue of slavery was always on the forefront. Northern Whigs and Republicans didn't need to make slavery a wedge issue. People were as passionate about slavery as they are today about abortion. People who wanted slavery abolished didn't want more slave states in the union because it would shift the balance of power toward slave states, vice versa for the people who supported slavery. They were driven by their support or opposition to slavery, not some revisionist, southern apologist agrarian issues.