Books like God Is Not One
Stephen R. Prothero
God Is Not One is 388 pages, about 7 hours 7 minutes at 250 words a minute.
6 books to read next
How long each takes
The World's Religions 7.3 h 
Dictionary of All Scriptures and Myths 15.5 h 
Living Buddha, Living Christ 4.0 h 
AQA A-Level Religious Studies Year 2 7.2 h 
Swami Vivekananda 3.4 h 
The Unknown Christ of Hinduism 3.6 h Bar height shows length. Estimated at 250 words a minute.