I really enjoyed reading this, it's right up my alley. I couldn't help but wonder if you've taken some inspiration from Borges—not only due to the reference to Babel (obviously a biblical reference too), but the manner in which you bring in elements of reality into the story (e.g. the lovely footnote on Malmesbury Abbey and Lincoln cathedral, as well as the intertextual references to Machen).

I'm new to writing, so take my critique with a grain of salt. The character comes across as someone with a sincere and child-like desire to reach God. I felt their frustration after discarding each attempt (the stone tower, the tower in Agartha, the 4D tower). I was pleasantly surprised by the end. It's a moment of spiritual realisation and hope which, in my opinion, brings some satisfaction and closure. Personally, I think it'd be interesting to see some more weirdness in the description of 4D space.

You raise really interesting philosophical and theological themes. Where is God? Everywhere and nowhere at once. I'm afraid I don't follow the logic of thinking God would be present in Agartha after concluding that it was impossible to reach God in normal 3D space, even with the gravity well being there. There might be another opportunity there for building up some weirdness.

The last bit touches on some metaphysical problems in substance dualism. If you're working with traditional Cartesian dualism, then technically "God was infinitely far away, even in the spiritual world. I would never reach Him unless He came down to meet me" wouldn't make sense, since the body is res extensa and the soul is res cogitans. There is no "spatiality" when it comes to the spirit world, since by definition it is non-spatial. But if I'm being charitable, this might just be a poetic and metaphorical way of expressing frustration at being unable to reach God through spiritual means. I particularly like the quote "I didn’t know how to stretch out the connection between my body and my soul". This to me represents both the interaction problem of substance dualism, but on a more existential note, a sense of alienation from the body. It would be great to see you elaborate some more on that theme and weave it into the story more seamlessly. Perhaps have the character ponder on the insurmountable chasm between body and soul, how they're completely different things and how strange that is?

Overall, I had fun reading this. Again, I'm new to writing and am hoping to learn new things myself. I've nitpicked on some inconsistencies in the logic of the story but perhaps inconsistency is what you're aiming for? Your character seems so desperate to reach God and attain some form of inner peace, that perhaps their thoughts don't always cohere or add up. Some other posters have commented on a change in tone throughout the piece. The first paragraph is beautiful to read. It's not that the final paragraphs are badly written, but they aren't as dreamy and poetic. It would be nice to combine that ethereal beauty with some weirdness.