Don't know whether this topic has been brought up before, but I had a few thoughts to share.

1) In the World as Myth novels, people "survive" by having their memories channeled into new brains in new bodies, which were created from cloning. People also are created by channeling the memories of computers into bodies created from the DNA of naturally-born people. Where in all this is the soul? Doesn't seem like the surviving oldsters nor the former computers would have them. So, RAH may be saying that the idea of a soul is a non-starter; it's people's memories (time binding) that count.

2) On the other hand, in many of his novels, living characters are visited by the dead -- and not just Martians. In Farmer in the Sky, Billy's deceased mother talks to him in a dream. In Citizen of the Galaxy, Thorby is visited by Baslim and Grandmother in a dream. To me, this argues for Heinlein's belief in the continuance of personality through the soul. It might also indicate a belief that the physical world and the metaphysical world intersect through dreams.
I'm sure you could name other stories where living characters are visited by the departed in dreams, most notably, of course, in Stranger In a Strange Land, but I thought I'd skip that, because of the satirical nature of the work. In The Moon Is a Harsh Mistress, Manny in his old age supposedly hears Mike late at night, but I don't count this, either, because I contend Mike never died (having gained full maturation, he knew he had to cut off human contact so the Lunar Government wouldn't depend on him as a crutch), and Mike actually is whispering to Manny through the phone lines, I guess.

Anybody else want to weigh in?
For the record, I do not believe in the soul.

You've omitted a major example, IWFNE. Although he does give just enough reason to think that maybe it was a hallucination.

Never read I Will Fear No Evil all the way through, just too painful, so of course I never think about it. Thanks for pointing that out.
But what do YOU think? Did RAH believe in the soul, or not?

On most spiritual/religious issues, Heinlein was agnostic. He tended to find specific belief systems ridiculous, interesting, sublime, evil, or functional madness depending on that system, but his viewpoint characters (like Lazarus Long) constantly expressed the belief that a) we don't know what happens after death and b) when we die, we'll find out.

I'm a practicing Christian; of course I believe that human beings have souls. However, Heinlein's attitude about this strikes me as eminently sensible for those who "don't get it" about belief in God or simply don't believe what can't be empirically verified. He wasn't hostile to the idea, just sceptical about most forms of it that he encountered.

"Don't know who's turning the crank, just hope he doesn't stop." Maybe that's the best expression of Heinlein's belief.

Good old Manny.

In the biography (this is from memory but I'm 99.99% sure) Heinlein is quoted as writing that he believed that death is not the end. I'll have to find the cite later, but I took it as pretty definitive that he believed in something, though whether he called it a soul I am not sure.

Heinlein definitely hoped for something more than one human life; comments about that can be found throughout his books. What I never saw was anything that indicated that he accepted any *specific* beliefs on what that "more than" might consist of.

Maybe he was hoping someone would take him up on the Long family's rejuvenation research. Thank goodness he didn't opt for the Ted Williams solution.

He was asked about it. I forget where I read it, but his answer (to the fan suggesting cryogenic storage) was, "How do I know it won't interfere with reincarnation?"