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.
Rah’s second wife was named Virginia. Ginny.