The Stars. my destination.
I liked Heinlein a lot. But even Heinlein ended up becoming a Deist. I came to Jesus when I realized that even with my best efforts, I still needed forgiveness. I made mistakes. Everyone does.
Based on the first volume of the Heinlein biography, I'd call him more of an experimental pantheist, with some weird friends. Jack Parsons and L. Ron Hubbard were in the circle of people he knew. His second wife*, Leslyn, was a witch of some sort.
I await the second volume.
*First marriage was very brief, just after his Naval Academy days.
I’m not sure Deism explains RAH, at least in his later and weirder years.
Best I can figure is he had some notion that the universe (or universes) came into existence because sentient beings believe in them. Sort of a Tinkerbell approach to Creation.
This of course makes those who create the stories which become creation myths into God. Which of course is flattering to writers of stories.
Pretty much everything he wrote after 1973 is garbage. Some of it interesting garbage, to be sure.