Messenger's job secured by porter (7)
I believe the answer is:
apostle
'messenger's' is the definition.
(the apostles spread Jesus' message)
'job secured by porter' is the wordplay.
'job' becomes 'post' (post is a kind of job).
'secured by' indicates putting letters inside (I've seen this in other clues).
'porter' becomes 'ale' (I've seen this in other clues).
'post' placed inside 'ale' is 'APOSTLE'.
(Other definitions for apostle that I've seen before include "Good man" , "Vigorous campaigner" , "Holy person" , "Preacher perhaps" , "Leaps to find religious follower" .)