The Attorney General, Dominic Grieve, who's a patron of the Conservative Christian Fellowship, has said people in Britain by a very "substantial margin" have religious belief in the "supernatural or a deity".
He also blamed the "rise of religious fundamentalism" for deterring people from expressing their Christianity, saying it was a very "damaging" turn off.
Mr Grieve's decision to speak out comes only days after over 50 public figures, including novelists, scientists, broadcasters, campaigners, authors and comedians wrote to the Prime Minister challenging his position on the matter.
The letter, organised by the British Humanist Association, criticised Mr Cameron by pointing to surveys, polls, and studies in which they claimed had shown most Britons "were not Christian at a social level", and that Britain has been shaped "for the better" by many pre-Christian, non-Christian, and post-Christian forces.
Iain Duncan Smith, the Work and Pensions Secretary, who also follows the Christian faith, defended Mr Cameron, describing the comments as "absurd" saying his critics were "ignoring both historical and constitutional reality".
He said: "The idea that his comments have alienated those of other faiths is questionable given the range of religious leaders from other denominations who have welcomed them.
"It is arguably our Christian heritage, with its innate tolerance and inclusivity, that has ensured the freedom of all voices - religious or non-religious - to be heard and to be valued."
However, lecturer Dr Anthony McRoy told Premier's Marcus Jones on the News Hour why he believes Christians need to do more to get their message across.
In a statement, the Church of England also praised the Prime Minister's position by saying "arguing for an inclusive national identity focusing on the common values that unite us rather than one narrow identity which we don't share is not motivated by anti-religious sentiment but by a genuine concern for social solidarity".
The 2011 census showed that 59 per cent of people in England and Wales - or 33.2 million people - identified themselves with Christianity.
However, those reporting "no religion" almost doubled from just under 15 per cent to more than 25 per cent.