Joseph Smith boasted that he did more than Jesus to keep a church together.
"God is in the still small voice. In all these affidavits, indictments, it is all of the devil--all corruption. Come on! ye prosecutors! ye false swearers! All hell, boil over! Ye burning mountains, roll down your lava! for I will come out on the top at last. I have more to boast of than ever any man had. I am the only man that has ever been able to keep a whole church together since the days of Adam. A large majority of the whole have stood by me. Neither Paul, John, Peter, nor Jesus ever did it. I boast that no man ever did such a work as I. The followers of Jesus ran away from Him; but the Latter-day Saints never ran away from me yet . . . " (History of the Church, vol. 6, p. 408-409).
Joseph Smith said the Book of Mormon was more correct than the Bible.
"I told the brethren that the Book of Mormon was the most correct of any book on earth, and the keystone of our religion, and a man would get nearer to God by abiding by its precepts, than by any other book," (History of the Church, vol. 4, p. 461).
Joseph Smith made a false prophecy (one of several).
". . .I prophesy in the name of the Lord God of Israel, unless the United States redress the wrongs committed upon the Saints in the state of Missouri and punish the crimes committed by her officers that in a few years the government will be utterly overthrown and wasted, and there will not be so much as a potsherd left . . . " (History of the Church, vol. 5, p. 394).
Joseph Smith said mothers have babies in eternity and some are on thrones.
"A question may be asked, ‘Will mothers have their children in eternity?' Yes! Yes! Mothers, you shall have your children," (Journal of Discourses, vol. 6, p. 10). "Eternity is full of thrones, upon which dwell thousands of children reigning on thrones of glory, with not one cubit added to their stature," (Journal of Discourses, vol. 6, p. 10).
Joseph Smith said that God was not always God.
“We have imagined and supposed that God was God from all eternity. I will refute that idea, and take away the veil, so that you may see. These are incomprehensible ideas to some, but they are simple. It is the first principle of the Gospel to know for a certainty the Character of God, and to know that we may converse with him as one man converses with another, and that he was once a man like us; yea, that God the Father of us all, dwelt on an earth, the same as Jesus Christ himself did, and I will show it from the Bible” (Teachings of the Prophet Joseph Smith, pp.345-346. Italics in original).
Joseph Smith said there are many gods.
"Hence, the doctrine of a plurality of Gods is as prominent in the Bible as any other doctrine. It is all over the face of the Bible . . . Paul says there are Gods many and Lords many . . . but to us there is but one God--that is pertaining to us; and he is in all and through all," (History of the Church, vol. 6, p. 474). "In the beginning, the head of the Gods called a council of the Gods; and they came together and concocted a plan to create the world and people it," (Journal of Discourses, vol. 6, p. 5).
Joseph Smith said the Trinity is three gods.
"I have always declared God to be a distinct personage, Jesus Christ a separate and distinct personage from God the Father, and the Holy Ghost was a distinct personage and a Spirit: and these three constitute three distinct personages and three Gods," (Teachings of Prophet Joseph Smith, p. 370).
Joseph Smith said God was once a man.
"God himself was once as we are now, and is an exalted Man, and sits enthroned in yonder heavens...I say, if you were to see him to-day, you would see him like a man in form -- like yourselves, in all the person, image, and very form as a man....it is necessary that we should understand the character and being of God, and how he came to be so; for I am going to tell you how God came to be God. We have imagined and supposed that God was God from all eternity, I will refute that idea, and will take away and do away the veil, so that you may see....and that he was once a man like us; yea, that God himself the Father of us all, dwelt on an earth the same as Jesus Christ himself did." (Journal of Discourses, vol. 6, p. 3).
Joseph Smith said our greatest responsibility is to seek after our dead.
"The greatest responsibility in this world that God has laid upon us is to seek after our dead," (Journal of Discourses, vol. 6, p. 7).
Joseph Smith said that there are men living on the moon who dress like Quakers and live to be nearly 1000 years old.
Since he was wrong about the moon, is it safe to trust him regarding the way to Heaven? (The Young Woman's Journal, vol. 3, p. 263-264. See reprint in Mormonism -- Shadow or Reality? by Jerald and Sandra Tanner, p. 4.)