The holy book is a shield slot item that is aligned with Saradomin. The book can be purchased from Jossik after completing Horror from the Deep.
When lost it can be reclaimed by speaking to Jossik in the Lighthouse. Alternatively players can pay Perdu 12,000 coins and save the trip.
The holy book is created from the damaged Saradomin God book. Adding all four Saradomin pages creates the unholy book.
The pages required are Saradomin Page 1, 2, 3, and 4. These pages can be found by completing Treasure Trails or by buying them on the grand exchange.
+8 stab defense
+8 slash defense
+8 crush defense
+8 magic defense
+8 ranged defense