Clue: In a religious sense, he believes in coasting freely (8)
Answer: AGNOSTIC
Explanation: Definition: In a religious sense, he believes
An anagram ('freely') of 'coasting'. The definition is rather peculiar. Chambers gives for the noun: A person believing that we know nothing of things beyond material phenomena, that a Creator, a creative cause and an unseen world are unknown or unknowable; a sceptic.
 This contains the word "believing", but how to reconcile it with the definition in the clue, I do not know. The possibility of an extended definition seems equally off the mark.