MRMOVES - I was reading one of the questions in the faq where one person asks....
JOHN - "Asks whether President Hinckley contradicts Joseph Smith's concept about God once being a man" At one point you answer.......President Hinckley could not say that we believe God was once a man like us, because it has never been identified as official Church doctrine....
I was reading the book, " Preparing for a celestial marriage" where it bluntly talks about that God was once a man and that he was once like us, and I know that is a approved Church Manual. I know it is stated in the first few lessons in that book.

JOEL - I think you are right as far as members of the Church are concerned. The concept of God once being a man is accepted as doctrine. This concept does show up in the Church produced "Gospel Principles" manual:

"The Prophet Joseph Smith taught: “When you climb up a ladder, you must begin at the bottom, and ascend step by step, until you arrive at the top; and so it is with the principles of the Gospel—you must begin with the first, and go on until you learn all the principles of exaltation. But it will be a great while after you have passed through the veil [died] before you will have learned them. It is not all to be comprehended in this world; it will be a great work to learn our salvation and exaltation even beyond the grave” (Teachings of the Prophet Joseph Smith, p. 348).
This is the way our Heavenly Father became God. Joseph Smith taught: “It is the first principle of the Gospel to know for a certainty the character of God. … He was once a man like us; … God himself, the Father of us all, dwelt on an earth, the same as Jesus Christ himself did” (Teachings of the Prophet Joseph Smith, pp. 345–46).
Our Heavenly Father knows our trials, our weaknesses, and our sins. He has compassion and mercy on us. He wants us to succeed even as he did." (Chapter 47: Exaltation, Gospel Principles, 301)

We know that the concept is definitley not well describe in the four standard works. But does the fact that past prophets have believed it and we use their statements to describe it in a teaching manual, make it "official" Church doctrine as far as the world is concerned; or does it only make it a doctrine that we accept amongst fellow members within the Church as being true? Can we really call it an "official" core tenet of the Church to the entire world, when we have so little understanding of the concept ourselves?
The Church recently explained where official doctrines of the Church are found:

"Not every statement made by a Church leader, past or present, necessarily constitutes doctrine. A single statement made by a single leader on a single occasion often represents a personal, though well-considered, opinion, but is not meant to be officially binding for the whole Church. With divine inspiration, the First Presidency (the prophet and his two counselors) and the Quorum of the Twelve Apostles (the second-highest governing body of the Church) counsel together to establish doctrine that is consistently proclaimed in official Church publications. This doctrine resides in the four “standard works” of scripture (the Holy Bible, the Book of Mormon, the Doctrine and Covenants and the Pearl of Great Price), official declarations and proclamations, and the Articles of Faith." (See this link)

So according to the statement above, is this doctrine(God once being a man) "consistently proclaimed in official Church publications" and does it "reside in the four “standard works” of scripture, official declarations and proclamations, and the Articles of Faith" ?
The concept might be mentioned in one or two church manuals or other publications, but does that satisfy the criteria of "consistantly proclaimed"?
In my opinion it is not adequately explained in the scriptures or by past prophets to a degree that allows us to tell the world that it is one of our core tenets, even though it may be a true doctrine. I have heard many varied opinions on this subject.