David Whitmer was a powerful figure in the early Mormon Church. Besides being one of the Book of Mormon Witnesses, he was in the Missouri Presidency and (some believed) ordained to be Joseph Smith’s successor in 1834. He was released from his Missouri position in 1837 and was excommunicated from the Church in 1838.
In his Address to All Believers in Christ, a pamphlet he published in 1887 when he officially formed the Church of Christ, he made clear his reservations about Joseph Smith and the other Mormon groups. The following is just a part of his critiques of the Mormon Prophet and those who claimed to follow him.
We do not indorse [sic] the teachings of any of the so-called Mormons or Latter Day Saints, which are in conflict with our Lord and Savior Jesus Christ, as taught in the New Testament and the Book of Mormon. They have departed a great measure from the faith of the CHURCH of CHRIST as it was first established, by heeding revelations given through Joseph Smith, who, after being called of God to translate his sacred word–the Book of Mormon–drifted into many errors and gave many revelations to introduce doctrines, ordinances and offices in the church, which are in conflict with Christ’s teachings. They also changed the name of the Church…On account of God giving to Joseph Smith the gift to translate the plates on which was engraven the Nephite scriptures, the people of the Church put too much trust in him–in the man–and believed his words as if they were from God’s own mouth. They have trusted in the arm of flesh…They looked to Joseph Smith as lawgiver, we look to Christ alone, and believe only in the religion of Jesus Christ and not in the religion of any man.
The doctrine of polygamy was not introduced until fourteen years after the church was established; but other doctrines of error were introduced earlier than this. I left the body in June, 1838, being five years before polygamy was introduced.
Joseph Smith drifting into errors after translating the Book of Mormon, is a stumbling-block to many, but only those of very weak faith would stumble on this account. Greater abominations are recorded of David in the Bible, than is recorded to-day of Joseph Smith; but do you reject the Psalms on this account? Do you reject the Proverbs because Solomon was a polygamist? Stop and think, you who are hasty to condemn. If you desire to know whether or not the Book of Mormon is true, read the book and investigate it, for Christ has promised that he who seeks in the right way shall find the truth of all things…
The Reorganized Church of Jesus Christ of Latter Day Saints, believe that Joseph Smith was a true prophet up to his death, and accept his revelations in their Book of Doctrine and Covenants. The revelation to practice polygamy is not printed in their Doctrine and Covenants. They do not believe in the doctrine of polygamy.
The Church of Jesus Christ of Latter Day Saints (the church at Salt Lake City) believe that Joseph Smith was a true prophet up to the time of his death, and accept his revelations which they have published in their Book of Doctrine and Covenants. In this book is the revelation on polygamy.
It is also a stumbling-block to those who desire to investigate as to the truth of the Book of Mormon, to see the believers in that book divided; but the divisions have been brought about by the revelations of Joseph Smith. We, the Church of Christ, who accept on the Bible and the Book of Mormon as the rule and guide to our faith, agree on the doctrine and gospel of Christ.
From this excerpt, Whitmer’s critiques are made clear: he believed Joseph Smith was a fallen prophet and that the two main groups claiming him as their founder (the LDS and the RLDS) were in error for putting too much trust in him. Whitmer obviously believed that Smith had begun practicing polygamy, though not until 1844, and that the Utah Mormons were continuing in that sin while the Reorganized Church flatly ignored it. His Church of Christ, however, was superior because they focused on the teachings of Christ alone rather than the arm of flesh.
I find Whitmer’s take on Joseph Smith quite interesting, particularly his comparison between him and David and Solomon. While Whitmer felt Smith had gone astray, he could not consider him a complete fraud because of Whitmer’s strong experience with the Book of Mormon. Therefore, in order to remove this “stumbling block,” Whitmer likens Smith to the Old Testament Patriarchs who were called of God yet still fell to carnal desires. This gives his “fallen prophet” claims precedence: Prophets had fallen in the past after fulfilling part of God’s commands, and Joseph Smith was just a modern expression of that story. Another great example of early Mormons placing themselves within the Biblical text.
Does anything else stick out to you, dear JI readers?
 David Whitmer, An Address to All Believers in Christ (Richmond: Published by Author, 1887), 4-5.