Christians in favour of both parts of Bible, except for this writer (11)

I believe the answer is:

protestants

I'm a little stuck... Click here to teach me more about this clue!

'christians' is the definition.
(Protestant is an example)

'favour of both parts of bible except for this writer' is the wordplay.
I cannot quite understand how this works, but
'of' could be 'o' and 'o' is present in the answer.
'parts' could be 'tes' (te is a kind of part) and 'tes' is found within the answer.
'bible' could be 'nt' and 'nt' is found in the answer.
This explanation may well be incorrect...

'in' is the link.

Can you help me to learn more?

I've seen this clue in The Telegraph.

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