On Mormon theology, God started as a human on another planet, but later obtained godhood by worshipping and obeying his god.
• Milton R. Hunter: “Mormon prophets have continuously taught the sublime truth that God the Eternal Father was once a mortal man… He became a God by absolute obedience…” [The Gospel Throughout The Ages, 104, 115.]
• Orson Hyde (Original President of the Quorum of the Twelve Apostles): “Remember that God, our heavenly Father, was perhaps once a child, and mortal like we ourselves, and rose step by step in the scale of progress, in the school of advancement; has moved forward and overcome, until He has arrived at the point where He now is” [Journal of Discourses, vol. 1:123.]
• Joseph Smith (Mormonism's founding president-prophet): “…you have got to learn how to be Gods yourselves, and to be kings and priests to God, the same as all Gods have done before you,” [Journal of Discourses, vol. 6:4.] (cf.History of the Church, vol. 6:476.).
• Brigham Young (Mormonism's 2nd president-prophet): “[He] passed the ordeals we are now passing through; he has received an experience, has suffered and enjoyed, and knows all that we know regarding the toils, sufferings, life and death of this mortality” [Teachings of Presidents of the Church: Brigham Young (1997), 29.]
• B. H. Roberts (Mormon Apostle & church historian): “But if God the Father was not always God, but came to his present exalted position by degrees of progress as indicated in the teachings of the prophet, how has there been a God from all eternity? The answer is that there has been and there now exists an endless line of Gods, stretching back into the eternities, that had no beginning and will have no end. Their existence runs parallel with endless duration, and their dominions are as limitless as boundless space.” [A New Witnesses for God 1:476]
• Joseph Fielding Smith (Mormonism's 6th president-prophet): “God is an exalted Man... The Prophet taught that our Father had a Father and so on.” [Doctrines of Salvation 1:10, 12]
• Heber C. Kimball (Member of the First Presidency): “then we shall go back to our Father and God, who is connected with one who is still farther back; and this Father is connected with one still further back, and so on…” [Journal of Discourses vol. 5:19.]
• Bruce R. McConkie (LDS 'General Authority'): “Elder William W. Phelps teaches very effectively the endless nature of all good things: If you could hie to Kolob… D'ye think that you could ever, Through all eternity, find out the generation Where Gods began to be?” [Mormon Doctrine (1958), 163-164.]
• Orson Pratt (Original 'Quorum of the Twelve' member): “We were begotten by our Father in Heaven; the person of our Father in Heaven was begotten on a previous heavenly world by His Father; and again, He was begotten by a still more ancient Father; and so on, from generation to generation, … we wonder in our minds, how far back the genealogy extends, and how the first world was formed, and the first father was begotten” [The Seer, 132]