If you’ve read the Lord of the Rings books, you’ll have noticed that Tolkien created a deep and extensive mythological backstory for his world. If you’ve read The Silmarillion, you saw this mythology play out on the page, from the creation of the whole universe and the planet of Arda, up through the end of the Third Age, which is the end of the LotR story.
Tolkien’s mythology draws a lot from both Catholicism and ancient Norse religion. As he was a follower of the former and a scholar of the latter, it’s been argued that the story of Arda was his attempt to reconcile the two. Whether this is true or not, it’s undeniable that Tolkein was inspired by the two belief systems when he created the history of Middle-Earth.