No. Have you ever known any large, diverse group of people to be of a unified opinion about anything?
Yep, Not all had to be against slavery. They may have had their own veiws but they all had to obide by the laws for the North.
No- not all Southerners were pro-slavery, just like not all Northerners were anti-slavery.
Federalists
Northerners were completely against slavery, and before the Civil War they took their hatred overboard by killing Southerners for their slavery.
Because the war was not about slavery - until Lincoln decided to turn it into a moral crusade, in order to keep the British from helping the Confederates. If most Northerners had been against slavery, there would not have had to be a dedicated 'Abolitionist lobby'.
The Secession and the Confederate attack against Fort Sumter.
A large amount of America's Christians and Quakers lived in the North in the past and were against slavery and abuses because of ethics.
Not all Northerners supported ending slavery. While many were abolitionists advocating for immediate emancipation, others were indifferent or held racist attitudes, opposing slavery primarily because of its economic competition with free labor. Additionally, some Northerners were concerned about the implications of ending slavery on social and political stability. Therefore, views on slavery varied significantly across the Northern states.
Some northerners believed slavery was morally wrong. Southerners believed slavery was an essential part of their lives.
Slavery was not much of a problem in the north so most northerners were against it uniting then into a union
Because most Northerners were against the extension of slavery, though they were prepared to accept it in its traditional heartlands.
Most Northerners were not Abolitionists, and there was no particular name for them. As the war went on, the anti-war Democrats were called Copperheads. These were pro-slavery.