According to scholar David John Buerger, Brigham Young clearly taught that

"Adam was the father of the spirits of mankind in addition to being the first procreator of mankind's physical bodies; that Adam came to this earth as a resurrected and exalted being; that he 'fell' to a mortal state of existence in order to procreate mortal bodies; and that Adam was the spiritual and physical father of Jesus Christ." (Dialogue, vol. 15, no. 1, p. 45)

According to the Institute for Religious Research,

"While not a doctrine believed by most LDS people today, there can be no doubt that Brigham Young believed and taught that Adam was God the Father, the God of this earth, and the Father of Jesus in the flesh. President Young taught this for over 20 years, claiming it was from the Lord, only to have later Mormon Prophet Spencer W. Kimball declare this false doctrine."

Mormon Mark Butler puts it bluntly:

"[T]he historical record does rather more than suggest Brigham Young taught Adam God. He gave a rather extensive discourse on the subject in General Conference on October 8, 1854. This caused a big controversy that kept it from becoming the doctrine of the Church and instead transformed it from official mystery to official denial to official heresy to official mystery again over the past one hundred and fifty years."

Mormon apostle Bruce McConkie states that if anyone teaches a false doctrine like Adam-God, then he will be damned:

"You talk about teaching false doctrine and being damned. Here is a list of false doctrines that if anyone teaches he will be damned. And there is not one of these that I have ever known to be taught in the Church, but I am giving you the list for a perspective because of what will follow. Teach that God is a Spirit, the sectarian trinity. Teach that salvation comes by grace alone, without works. Teach original guilt, or birth sin, as they express it. Teach infant baptism. Teach predestination. Teach that revelation and gifts and miracles have ceased. Teach the Adam-God theory (that does apply in the Church). Teach that we should practice plural marriage today. Now, any of those are doctrines that damn" (Sermons and Writings of Bruce R. McConkie, p. 337).

BYU professor Stephen E. Robinson summarizes the popular Mormon approach to the problem:

"So how do Latter-day Saints deal with the phenomenon? We don't; we simply set it aside. It is an anomaly." (Are Mormons Christians?, p. 19)

Mainstream LDS

• The Position of Adam in Latter-Day Saints Scripture and Theology, by Rodney Turner - "A thesis submitted to the faculty of the division of religion of Brigham Young University in partial fulfillment of the requirements for the degree of the master of arts"
• Brigham Young's Teachings on Adam (PDF), by Matthew B. Brown (2009 FAIR presentation)
• Adam-God's Last Stand, by W. John Walsh
• What About the Adam-God Theory?, by Van Hale (fringe Mormon)
• Bruce McConkie's Letter of Rebuke to Professor Eugene England
• Can Anyone Articulate Adam-God?, by Sam MB (ByCommonConsent.com)
• Adam-God: Thoughts and Reconciliations (PDF), by Nathan Oman
• Six Reactions to the Adam-God Theory, by Brian C. Hales
• Fundamental Teachings About Adam - The First Man, by Brian C. Hales
• Different Thoughts - Adam-God, by Elden Watson

Other

• Conflict in the Quorum: Orson Pratt, Brigham Young, Joseph Smith, by Gary James Bergera (Signature Books, 2002)
• The Adam-God Doctrine (PDF), by David John Buerger - From Dialogue, volume 15, number 1, Spring 1982.
• "Adam-God" - Brigham Young's Theory or Divine Doctrine?, by Bill McKeever (Mormonism Research Ministry)
• The Adam-God Doctrine, by Jerald and Sandra Tanner
• Another botched joke?, by Bill McKeever
• Adam-God doctrine (Wikipedia)
• Adam-God Doctrine (MormonThink)