I don't see the religious figure comparison, and I don't think they'd go that direction with her. Owens mentions the people at the NINA Project view El as somewhat of a celebrity, primarily because they've been working to prepare for her arrival for a long time and seeing her finally there is kind of a "holy shit she's actually here now" moment for them.
As for whether or not El's fight with 001 created the Upside Down or if it already existed, it's unclear right now and I think there are arguments for both sides. Interestingly enough, there's
a new interview from Variety with the Duffers that came out today where they specifically ask this: "
At what point in the timeline does Eleven create the Upside Down in relation to when the series starts?" to which the Duffers give a detailed answer about El's age but don't say anything about Variety throwing in the bit about Eleven creating the Upside Down.
I did find it interesting that the part where 001 is being thrown in the air in the Upside Down was a really narrow volcanic looking place with lots of lightning, almost as if it was still being formed while 001 was being flung into it. That's just speculation on my part but it looked much different than when we typically see the Upside Down. That being said, the Mind Flayer is kind of the biggest question mark right now. We don't know anything about its origin and it's been laying low letting Vecna do everything this season so far. If we find out the origins of the Mind Flayer then I think that'll probably be the answer to a lot of questions around the Upside Down that people have had, but I feel like that may be something they leave for S5.
