Good evening Robert in SD! I hope your day has been a good one.
Regarding Mormon theology, I understand that the belief is that the trinity is three separate gods, Father Son and Spirit - who are one in understanding (or one in mind and act).
The distinction is that Father, Son, and Spirit under Catholic theology are One God in three distinct persons… God without beginning and without end; eternal in nature - each having existed always, whereas, I understand the LDS trinity to be three separate divine beings who are themselves members in a long chain of exalted beings. The Father was once a human being with a beginning… who was exalted because of his obedience to his Heavenly Father, and thus he became our Heavenly Father, and the Son is the first of His children (by a Heavently Mother). The Holy Spirit is also a child of the Heavenly Father and Heavenly Mother, but without corporeal being (a spirit child). I do not know if this is all speculation on the part of LDS theologians, or if this is doctrine. However, it’s out there to read about and I’m certainly willing to listen to the LDS explanation as to whether it is accurate or not.
Peace,
Robert
First, thank you for the charitable tone of your post.
I think in many parts you have your Mormon understanding of the Godhead correct, but in other parts not so correct. (Not that I’m holding this against you

).
It is important to understand that Mormons believe all of us are Intelligences. We, as individuals, have existed forever. Because there is no dogmatic clarification, however, there are various interpretations of this in Mormonism in general. So, keep in mind that I am providing you my understanding of this subject matter. What is clear is that Intelligences are not or can they be created (D&C 93:29). What is clear also is that God is the greatest of all intelligences (Abr. 3:19). I bring this up only to clarify that in Mormonism there never is a time when God does not exist.
In so far as God not being always being a God. Here again we run in to an area that allows for some speculation. What is clear is that as far as we are concerned, God is infinite, eternal and everlasting (D&C 20:17). Joseph Smith made some statements that suggested that God was not always God. Some Mormons understand this to mean that God was once a person and then progressed to godhood. Other’s understand Joseph’s statements in the context of how Jesus Christ, who was both a God and a mortal man, progressed on earth until he was glorified and exalted. So, they would say that in this same way, God the Father, took upon him a mortal human body at one point, progressed as a mortal, and was glorified and exalted, all while still remaining God. I tend to favor the latter.
I think the late President of the Church, President Hinckley struggled with accepting the notion that God was once a man, like us. This becomes clear in interviews where the question was asked whether Mormons believe God the Father was once a man.
Q: There are some significant differences in your beliefs. For instance, don’t Mormons believe that God was once a man?
A: I wouldn’t say that. There was a couplet coined, “As man is, God once was. As God is, man may become.” Now that’s more of a couplet than anything else. That gets into some pretty deep theology that we don’t know very much about.
Q: So you’re saying the church is still struggling to understand this?
A: Well, as God is, man may become. We believe in eternal progression. Very strongly.
In the interview above, President Hinckley clearly accepts the idea that man can become as God is, however he doesn’t validate the notion that God the Father was once as man is.
In a seperate interview, again, when asked about the idea that God the Father was once a man, like us, Hinckley does not validate that notion.
“I don’t know that we teach it. I don’t know that we emphasize it. . . . I understand the philosophical background behind it, but I don’t know a lot about it, and I don’t think others know a lot about it.”
If nothing else, this should give you a good context of how this is viewed in Mormonism. We don’t know much about that notion. We definitely don’t emphasize it. We have canonized scripture upon canonized scripture, that tells us God is infinite and eternal. The statements made by Joseph Smith about God the Father have not been canonized. There has been no dogmatic clarifications given about them either. I would say most Mormons understand God to be infinite, eternal, and from everlasting to everlasting and if they speculate at all about what Joseph Smith wrote, they understand it in the context that God the Father experienced a mortal earth life in the same way that Jesus did, being at all times God.
Kind Regards,
Finrock