IIRC, the Charity Commission can investigate to establish if the organisation's charitable objectives are actually in-line with what qualifies as being a "chartitable objective" and also if the charity is fulfilling those objectives / obligations. It can be considered as fraud if a charity raises money under that 'objectives' umbrella and doesn't spend the money to [attempt to] achieve those objectives and instead spends it on something else.
As a result writing Charity objectives is a real PITA, you tie yourself into knots with being too specific / too general and tehn the CC picks holes in your efforts [and changes their criteria ] ...
for example - the RNLI as a charity "saves lives at sea" but could not use those 'general' funds to run specific museums / preserve historic artefacts & lifeboats [those aspects are now covered in a different way].
Personally, I think "Religion" as a "charity" in and of itself, as opposed to having "charitable purposes / objectives" needs very, very carefully examination and oversight.
And, that applies whatever flavour of religion is involved, whether that is a Christian, Islamic, Buddhist or 'whatever sect' is involved.