One of the reasons for the violent opposition to our members was most of them were opposed to slavery.

Quentin L. Cook
October 2021 General Conference
https://www.churchofjesuschrist.org/study/general-conference/2021/10/46cook?lang=eng

I will remark with regard to slavery, inasmuch as we believe in the Bible, inasmuch as we believe in the ordinances of God, in the Priesthood and order and decrees of God, we must believe in slavery. 

Brigham Young
Joint Session of the Legislature: January 23, 1852
https://mit.irr.org/brigham-young-we-must-believe-in-slavery-23-january-1852