I think that it would take many years to memorize the entire Bible (maybe shorter if only memorizing the New Testament). Numbers are easier than words, because there are systems designed for number memorization, like the Major System.
See also:
- John Basinger: Memorizing Milton's Paradise Lost
- Divina Commedia, and image density and Divina Commedia
- Has anyone memorized the entire Bible?
You could try memorizing a few of the shorter books to get an idea of how long it would take.