The implication in your comment is wholly incongruent with Mormon teaching.
Though Mormon teaching does believe in a requisite restoration - meaning that man cannot reform what only God can restore. That doesn’t however imply that ALL aspects of Christianity were erroneous since his mortal ministry. It, quite likely meant that MAN had made some mistakes along the way and that we might have straid from the objective. If that was the case Mormons would not teach and study the Bible as a canon of scripture at all but they do rather deliberately.
I’m pinging a few folks who have resources at their disposal which are not on my computer. What I will ask them to post are the actual quotes from Momronism’s founders and teachers who said that a complete apostasy existed which Smith was given to end. What these teachers taught was that ALL the denominations were corrupted. They taught that the notion of the Trinity was a demonic lie. They asserted that the Bible was okay, as far as it is translated correctly. And the current doctrines of Mormonism show that Mormonism is the only way to salvation in the ‘heaven of God’s presence’ because ONLY Mormon baptism can help save you, not Catholic baptism, not Presbyterian baptism, not Methodist baptism, ONLY Mormon baptism. And Mormonism has an entire elaborate proxy baptism for the dead which shows this error of ‘exclusivity’.