Teaching the absolute truth (6)
I believe the answer is:
gospel
I believe this is a double definition.
'teaching' is the first definition.
(gospel is a kind of teaching)
'the absolute truth' is the second definition.
(thesaurus)
(Other definitions for gospel that I've seen before include "Absolute truth" , "One of the first four Books of the New Testament" , "Black evangelical singing" , "God's honest truth" , "Christian doctrine" .)