how have the mormans treated black people historically?
Historically?
They fought for their right to equal treatment under the law,
they fought against slavery, and they had no problem sitting down to eat with them in public. Over all, they have a much better record, historically, than the Democratic Party that was on the other side on all of those issues. Why do you think the Democrats hate Mormons so emphatically?
Do you ever get tired of being wrong?
Pioneers and Cowboys
Slavery was legal in Utah as a result of the Compromise of 1850, which brought California into the Union as a free state while allowing Utah and New Mexico territories the option of deciding the issue by "popular sovereignty." Some Mormon pioneers from the South had brought African-American slaves with them when they migrated west. Some freed their slaves in Utah; others who went on to California had to emancipate them there.
The Mormon church had no official doctrine for or against slaveholding, and leaders were ambivalent. In 1836 Joseph Smith wrote that masters should treat slaves humanely and that slaves owed their owners obedience. During his presidential campaign in 1844, however, he came out for abolition. Brigham Young tacitly supported slaveholding, declaring that although Utah was not suited for slavery the practice was ordained by God. In 1851 Apostle Orson Hyde said the church would not interfere in relations between master and slave.
The Legislature formally sanctioned slaveholding in 1852 but cautioned against inhumane treatment and stipulated that slaves could be declared free if their masters abused them. Records document the sale of a number of slaves in Utah.
African Americans were not the only slaves bought and sold in the territory. The arrival of the pioneers in 1847 disrupted a thriving trade in Native American slaves. Utah-based Indians, particularly Chief Walkar's band of Utes, served as procurers and middlemen in a slave-trading network that extended from Santa Fe, New Mexico, to Los Angeles, California, and involved Spanish, Mexican, American, and Native American traders.
And let's not forget this little tidbit about Mormons...
They didn't allow blacks to be part of the priesthood (something all Mormon Males must do when they are young) until 1978.
By 1978, Strom Thurmond had blacks on his staff.
Not to mention, Mormon scripture considers dark skin a curse from God.
Now, to their credit, your average Mormon will wince when someone points these things out. They recently threw Brigham Young under the bus trying to blame him for a lot of this racism while giving Joseph Smith a Pass. But the Mormon Church has a horrible history on race.
But shit, the Mormon Church is one big honking lie, so it's hard to hold that against them.