Deliberate, one having finished absorbing religious books (8)
I believe the answer is:
intended
'deliberate' is the definition.
(similar in meaning)
'one having finished absorbing religious books' is the wordplay.
'one' becomes 'i' (Roman numeral).
'having' means one lot of letters go next to another.
'finished' becomes 'ended' ('end' can be a synonym of 'finish').
'absorbing' indicates putting letters inside.
'religious books' becomes 'NT' (New Testament).
'i'+'ended'='iended'
'iended' placed around 'nt' is 'INTENDED'.
(Other definitions for intended that I've seen before include "Informally one's fiance or fiancee" , "Fiancé (e) - on purpose" , "The boyfriend" , "One about to join union" , "Set out" .)