More than 50 prominent public figures including novelist, diplomats, Nobel prize winners and playwrights have accused David Cameron of fostering divisions in the UK by repeatedly referring to Britain as a Christian country.

Signatories to the letter asserting that Britain is not a Christian country include Philip Pullman, Ken Follett, Prof Alice Roberts, Prof Harold Kroto and Sir Terry Pratchett.

The authors say they respect Cameron's own religious beliefs but say they "object to his repeated mischaracterising of our country as a 'Christian country' and the negative consequences for our politics and society that this view engenders".

In a letter to the Daily Telegraph, they assert: "Apart from in the narrow constitutional sense that we continue to have an established church, we are not a 'Christian country'. Repeated surveys, polls, and studies show most of us as individuals are not Christian in our beliefs or our religious identities and at a social level, Britain has been shaped for the better by many pre-Christian, non-Christian, and post-Christian forces.

"We are a plural society with citizens with a range of perspectives and a largely non-religious society. To constantly claim otherwise fosters alienation and division in our society. Although it is right to recognise the contribution made by many Christians to social action, it is wrong to try to exceptionalise their contribution when it is equalled by British people of different beliefs. It needlessly fuels enervating sectarian debates that are by and large absent from the lives of most British people, who – as polls show – do not want religions or religious identities to be actively prioritised by their elected government."

Signatories also included the novelist Maureen Duffy, the Nobel prize-winning scientist Sir John Sulston, the scientist Sir John Blundell and the former diplomat Sir Richard Dalton.

Cameron has been more outspokenly Christian this Easter than on previous occasions, which many critics claim is a response to the political threat from Ukip.