Here's how Shattered Pixel Dungeon's mobile hero select screen will look with the upcoming Cleric added to it. Some visuals are still a WIP, (the cudgel's sprite in particular is very rough) but all the important bits are in place.
You can see the info window for the Cleric here too, showing off some info about their abilities. Just like the Rogue, the Cleric has a unique artifact that lets them access class abilities.
Unlike all the other heroes though, the Cleric gains a wide variety of active abilities (spells) via the talent system! I'll be sharing more info about some of the Cleric's spells in the coming weeks!
(Image Description: A screenshot from Shattered Pixel Dungeon showing the hero select screen and the Cleric selected. On the left the screen is shown with no info window open, on the right the hero info window is open, showing various information relating to the new hero. Most notably: "The Cleric starts with a unique holy tome, which they can use to cast various spells. Most of the Cleric's talents are focused around learning or upgrading spells.")
But mechanically, in Shattered Pixel Dungeon he doesn't, unless I missed something in an update (I don't usually play that class).
And yeah, calling it holy scripture would work fine. I just feel like calling it a spell book highlights the fact that the Sorceror is really just a wand/magic staff user and doesn't have much "spell" mechanics directly.
It is in fact called the 'holy tome' in game, I agree calling it spellbook would be confusing, especially as 'unstable spellbook' is already an artifact.