It appears this is not the answer, but I wanted to leave this here for future reference when people search the site:
To Die in Italbar (1973) by Roger Zelazny contains a similar scene. The last third of the novel was completely rewritten a few years later after Zelazny's first draft was rejected; with the revisions, he made the book a sequel to his 1969 novel Isle of the Dead.
As eventually published, both novels involve the gods of the alien Pei'ans pantheon. Most of the Pei'an's gods have Pei'an-like bodies, but some have the form of other alien races that the Pei'an spacefarer's have met; for example, Shimbo of Darktree, Shrugger of Thunders, is a human. In To Die in Italbar, some of the characters find their way into the ruins of a Pei'an temple, with the images of all the gods surrounding them on the walls. Eventually, a party physical, partly psychic battle takes place between two of the gods, who have incarnated themselves through humans.