Technically Mormons believe that they are the rightful Christians and everyone else is an apostate.
They reject the trinity and are basically polytheistic with god the father, son and Holy Spirit as separate gods out of many other gods. Not Christians. Christianity is strictly monotheistic. It’s pretty clear in the Bible that there is no other god but the Abrahamic god.
Their book and new prophet and revelation that supersede the Bible that no other church accepts.
Not to mention they think the garden of eden is in Missouri…and Jesus came back to North America.
Islam is closer to Christianity than Mormonism.