Oh dear, what a messy debate. Please correct me if I am wrong on any of the following:
(a) When people tick boxes on a census form or survey they may or may not be telling the truth - just trying to satisfy the powers-that-be and get rid of the paper nuisance maybe. If you were an atheist applying for a job and it was still legal to ask your religion I bet you would lie and say "christian" in the U.K., in case the interviewer was a devout religionist. I would because it's a trivial matter.
(b) Of course you can be ethnically jewish and atheist but you cannot be religiously jewish and an atheist - a contradiction in terms.
(c) Fanatical murderers asside, Islam is no threat to this or any other country - forget relative percentages, each man & woman will make up their own mind and most by far never consider religion as important, which it isn't. It's just about baptism and teaching lies.
(d) Religion worldwide is dieing thanks to our creation of new gods: TV celebs, a lust for cinema/TV violence and related inventions like the internet and mobile phones. Please note that TV's "Songs of Praise" shows full churches thanks to the TV cameras without which those churches would be virtually empty. We made our own gods over millenia. We destroyed them and replaced them at a "whim". Todays gods were made by us and we are now replacing them.
(e) Religion is horrifying to most mortals with its promise of eternal life (everlasting boredom or reincarnation as an earwig or spider).
So, emmie, David Cameron's voter "appeal" is a non-starter - a defo "NO" to your question which refers to an Eton/Oxford millionaire who does not understand unthinking yobs like us (pardon me emmie if the latter phrase is insulting and you are as out of touch as "Dave" is).
Kindest Regards,
SIQ.