Technically it's six books, but he was going to publish them as one volume until the publisher said "you can't do that"

The Bible has used the same structure as Tolkien.

It starts off with the Gospel/early testimonies:

• The Hobbit, or There and Back Again

Then the New Testament proper:

1. The Fellowship of the Ring
2. The Two Towers
3. The Return of the King

It then contains the "Old Testament", that fleshes out much of the older lore in the World. These writings are less firmly established, but are widely considered to include:

• The Silmarillion
• Unfinished Tales of Numenor and Middle-earth
• The Children of Húrin

Then you have books of Psalms, like The Adventures of Tom Bombadil and other stories.

Let's not forget the Epistles, the letters of the apostles, compiled under:
The Letters of J.R.R. Tolkien

I know who the Pope is! But you gon leave him out like you didn't?