As indicated in the most-upvoted answer here,
There is one exception though. If a question is asking for the
inspiration behind a work of fiction, answers citing religious texts
should be considered valid.
Many history-of questions ask for the first appearance of something "in a work of fiction" or "in sci-fi" or "in fantasy." For example, this and this. They are not asking for the "inspiration" of a concept (which might be real life, for example), but its point of origin in fiction. This is generally implied even when not stated explicitly.
In such cases, simply giving a religious answer, with no further clarification, doesn't really fit the bounds of the question, rather like answering a book question with a movie answer. The question is not asking for the real-world origin of a trope, but when it first appeared in a fictional work. You wouldn't answer What is the earliest example of a "Blighted Land" created by human or semi-human activity? with a scientific treatise about nuclear testing sites, so why answer it with a religious work?
Stating the first appearance of the trope in a fictional text, and then giving a religious, scientific, or historical text as the probable inspiration should be acceptable, though.
The first fictional appearance of this concept is in Y (describes Y). However, it is much older, with its roots in the mythology of X.
An alternative might be asking "What is the origin of trope X?," which could plausibly be tagged history-of or inspiration, and which would admit real-world/religious and fictional answers.
Q: "What is the origin of the trope of radiation making animals grow in size?"
A: "I'm pretty sure this actually happened in real life after nuclear tests."
A: "The Church of Our Lady of Perpetual Nuking first mentioned this idea in the 40s."
A: "Probably Godzilla."