Social trinitarianism I believe maintains the doctrine of creation ex nihilo and thus would take a similar stance.

As I’ve noted though Mormons believe that at least something essential to us is eternal and uncreated. So in a sense we end up moving human beings to a place where we are organized but uncreated.

All this does highlight the problem of being careful in how we talk about all this.

That’s kind of a tricky question if the Heavenly Father is immaterial. Jesus, though, presumably has a body in traditional non-LDS Christian thought.

The idea of separate beings has similarities to social trinitarianism, which some “mainstream” theologians have proposed. I’m not sure the idea itself is part of the mainstream, though.

I think part of the problem with dealing with what “mainstream” Christians believe is that so many of them (I’m not talking about seminary graduates here) believe in a type of modalism rather than the doctrine of the Nicene creed. It’s technically a heretical view, but common nonetheless.

I think Orson Pratt had a profound influence on 20th century Mormon thought. He adopted a kind of theological absolutism which JFS and BRM carried as well as a basically nominalistic approach to the issue. His approach to materialism wasn’t followed, mainly because B. H. Roberts adopted an immaterial Cartesian mind as the explanation of intelligence. However in most other areas Pratt’s ideas were taken up by both movements in the 20th century. (JFS’ views in particular were highly influenced by OP) I’d note that Pratt’s main theological opposition was Brigham Young yet in nearly every place they disagreed 20th century thinkers followed Pratt rather than young.

His ultimate materialistic ontology hasn’t been followed. As I said that’s partially because Roberts, Talmage and Widstoe modified it somewhat to have our basic intelligence – spirit -body trichotomy that most accept today: with intelligence being basically a disembodied Cartesian mind. I think there are problems with this view as well. I’d note that most thinkers of the last 20 years have been moving away from the Roberts view. (Noting, as Blake Ostler does, that in Nauvoo spirit and intelligence were used synonymously)

The other problem with Pratt is he adopted whole heartedly the idea of atoms as the ultimate constituents of matter as was widely believed in the mid-19th century. Of course physics has moved quite a way beyond that. First to field theories and then to finding more basic constituents of matter and then to our current understanding of quantum theory and general relativity. So his materialism which was so key to his thinking seems quite quaint and antiquated. Likewise his idea of spiritual fluid was highly influenced by the scientific notion of an aether which was disproven first by finding the speed of light was a constant and then completely replaced by Einstein’s theory of relativity. So Pratt’s key problem was trying, in a naive way, to reconcile Mormon theology to science.

Despite those problems I think it safe to say that the history of 20th century Mormonism is pretty much a history of the influence of Pratt’s way of conceiving Mormonism and a move away from the typical 19th century way of thinking. That’s changed somewhat the last 20 years as more early texts are read closely – especially those from Joseph’s Nauvoo. However this has led probably to more diversity of views than anything. I should also note that Pratt’s panpsychism (the idea that the substance of the universe has rudimentary sentience and can obey God) is more widespread among Mormons than I suspect many believe. It was widely discussed at BYU while I was there with no one even attributing it to Pratt as the source. (Although he was influenced by various other texts such as Moses 7) I don’t think it was help by the majority of Mormons – especially not with the number of converts we have who don’t read up on theology. But it was surprisingly widespread in the Wasatch region of the Church even if arguably it is among the most controversial of Pratt’s ideas.

Question for you: do mainstream Christians accept the idea that Jesus and Heavenly Father are really separate beings today, separate materially but unified in spirit and purpose?