This will probably make more sense to readers familiar with Christianity - climax totally escaped me except for a feel that those looking for god ended up finding devil (but I might be wrong in this interpretation).
But rest of the story - preclimax story - was readable, if not particularly noteworthy: a bunch of fanatics want their god to reappear at the new "Sinai" - so "the heathen, the idolators, will take heed and tremble."
And they have a practical way to make the god appear in physical form: a telepath with ability to call ... spirits, whatever ... on a world called "Kinsolving's Planet" at the edge of galaxy where time & space have funny properties. Experiment will result in an appearance, but not of god.
Related.I recall having read a story of Chandler I cannot recollect the title of that was a sort of prequel to this story. I don't recall a lot of details, but this story too happens on the same world at the edge of galaxy & something appears out of thin air, so to say. I think references to appearance of primitive man in this story are from there.
Fact sheet.First published: If, April 1968.
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Note: This Webscription version appears to be a minor fixup of original magazine version, but reads well enough as an independent story. This is the only version I've read.
Related: Stories of A Bertram Chandler.