Being all-powerful, I’m open to changing books (10)
I believe the answer is:
omnipotent
'being all-powerful' is the definition.
('omnipotent' can be a synonym of 'all-powerful')
'i'm open to changing books' is the wordplay.
'changing' indicates an anagram.
'books' becomes 'NT' (New Testament).
'im'+'open'+'to'='imopento'
'imopento' anagrammed gives 'omnipote'.
'omnipote'+'nt'='OMNIPOTENT'
(Other definitions for omnipotent that I've seen before include "All-powerful" , "Almighty" .)