M. Alis new religion (5)
I believe the answer is:
islam
'religion' is the definition.
(I know that Islam is a type of monotheism)
'm alis new' is the wordplay.
'new' indicates anagramming the letters.
'm'+'alis'='malis'
'malis' is an anagram of 'ISLAM'.
(Other definitions for islam that I've seen before include "Religious faith of Muslims" , "Faith with five pillars" , "Mohammed's religion" , "Religion of the Koran" , "Belief" .)