To him, sins destroyed religious belief (9)
I believe the answer is:
shintoism
'religious belief' is the definition.
(Shintoism is an example)
'to him sins destroyed' is the wordplay.
'destroyed' is an anagram indicator.
'to'+'him'+'sins'='tohimsins'
'tohimsins' is an anagram of 'SHINTOISM'.
(Other definitions for shintoism that I've seen before include "foreign religion" , "Japanese religion" .)