No, the bet was between L. Ron Hubbard and A.E. Van Vogt.
Heinlein's Stranger was a satire on the excesses of society he saw developing. He was by no means attempting to start a religion.
I posted above it was Arthur C. Clarke. I actually did some research and found that reference with a Google search. But Van Vogt kicked off a memory -- it sounded right -- so I searched a little more. I found the bet is said to have been with Joe Haldeman or Heinlein or John W. Campbell Jr. or??? Apparently no one can really pin it down. But now I recall reading years ago it was with Van Vogt. Remember "Slan?"