Tolkien and Lewis had some bizarro theories about universals myths which meant that to them, blatant Christian allegory was not actually allegory but just a retelling of eternal truths in the form of myths. But as a reader, we don't have to accept those theories. We can enjoy their stories as stories.
I think a lot of fantasy readers dislike allegory because it kind of turns reading into work and takes the escapism out of it, so it is nice when Tolkien in person validates this aversion. But be careful - you can enjoy Tolkien without caring about the underlying worldview, but that emphatically does not mean it is not there.
(Of course to me Christian mythology is just as much fantasy as Middle Earth, but it certainly was not like that for Tolkien)
Note I’m not criticizing Tolkien for this, I believe his power very much stem from the deliberate fusing of pre-Christian myths with a Christian worldview which leads it to a more straightforward engaging “good vs evil” narrative. I just find it hilarious when Tolkien fans uncritically buy the “there are no allegories” quip.
I guess my question is this. In some ways storytellers are trapped in that if you want to do good vs evil - you're going to reuse themes. Whether it's a single "abrahamic" God/Devil, or pantheons and aspects, you're going to step on some toes and parallels can be drawn. If you try and avoid that you're warping the story you want to tell for the fear of readers assuming intent etc and that strikes me as far worse than accepting that mythology is always going to have got there first.
I don't know, I've never really thought about this before or seen the allegory arguments he made.
So back to Tolkin. He was a linguist, so I guess he preferred to say things directly. If there are nebulous, abstract allegories to be seen, then because the concepts were intentionally not defined.
Rebirth is not an allegory for rebirth. What would the allegory be. Being chosen? Well, yeah, by the author.
Yes, there are some similarities but the entire story is markedly different. Jesus didn't die to come back as a more powerful Jesus 2.0 in order to defeat his former boss.
Gandalf's death had nothing to do with absolving the sins or saving the souls of humans. That's a fundamental aspect of Jesus' death and ressurection.
There are many more fundamental differences than there are similarities.
The point is not that there are differences. The point is that the differences are far more numerous and significant than the similarities.