High point of belief about church held by Poles (9)
I believe the answer is:
crescendo
'high point' is the definition.
(I've seen this before)
'belief about church held by poles' is the wordplay.
'belief' becomes 'credo' (credo is a kind of belief).
'about' indicates putting letters inside.
'church' becomes 'CE' (abbreviation for Church of England).
'held by' indicates putting letters inside.
'poles' becomes 'sn' (North and South poles).
'ce' inserted into 'sn' is 'scen'.
'credo' placed around 'scen' is 'CRESCENDO'.
'of' acts as a link.
(Other definitions for crescendo that I've seen before include "Increasing noise" , "Gradual increase in volume" , "Conceders (anag.)" , "Peak of intensity" , "Intensify" .)