David Cameron is mistaken when he says "Britain is a Christian country" and that we should be "evangelical" about Christianity.
That's why I joined over 50 prominent writers, scientists and academics to sign a critical letter to the Prime Minister.
The letter was organised by the British Humanist Association.
We acknowledge that Christians make a contribution to UK society but so do people of other faiths and no faith.
It is wrong for David Cameron to single out Christians for special praise, to offer them privileged access to Downing Street and to support an expanded role for Christian groups in providing essential public services.
He's also misguided to suggest Britain should be evangelise Christianity. This sounds like proselytising. It makes him comes across as partisan, favouring one faith over all others.
Britain was once a mostly Christian nation but no more.
A YouGov poll in 2011 asked: Are you religious? Only 29% said yes (and many of these belonged to non-Christian faiths). 65% said no.
The 2011 census asked a rather leading question on religion and got a different result. 59% said they were Christian. But most of these identify as Christian culturally, not religiously. Moreover, this is a big drop from the previous census in 2001, when 72% identified as Christian - a loss of 4.1million people claiming Christian adherence.
Ticking a box on a census form is easy. It is not the same as actually practising Christianity. It is religious practice, not tick boxing, that's the real test of whether we are still a Christian country.
In fact, only 7% of the population are practising Christians. A mere 2% go to church on Sunday. The number of practising Muslims in the UK is now almost as great as the number of practising Christians - around 2million versus 2.5million.
In addition, Christian anniversaries like Easter and Christmas are not celebrated by most people as religious festivals. They are just holidays like any other holiday - mostly an excuse for a lie-in, shopping, watching football and other non-religious indulgences. The vast majority of people don't pray or go to church on these occasions.
For all these reasons, by no stretch of the imagination can Britain be said to be a Christian country.
Britain is, in fact, a multifaith and no faith society. Christians are just one part of our plural, diverse culture. It is best for everyone, including people of faith, if the state is neutral on matters of religion; not favouring or privileging one religion over others. This way there is a level playing field for people of all faiths and none.
The idea the Britain has always been Christian is untrue. Humans have been in the British Isles for around 40,000 years. Christianity has been here for less than 2,000 years - a small fraction of British history.
Far from being the repository of great moral virtue and leadership, as David Cameron has suggested, the social and political influence of many Christians has been often malign. In feudal times, the churches supported the tyranny of absolute monarchs - and later slavery and colonialism. They opposed votes for women and gay equality. Indeed, only last year they fought an intolerant, bigoted campaign to retain homophobic discrimination and prevent same-sex couples getting married.
Some Christians have been very good on issues like poverty, welfare reform and justice for poorer countries. But many non-Christians have also been good on these issues. Commendable humanitarian organisations like the Child Poverty Action Group, War on Want and Amnesty International include people of all faiths and none.
Some of my critics claim that I and other humanists persecute Christians. Not true. On free speech grounds, I have been vocal in opposing the criminalisation and prosecution of Christian street preachers, such as Harry Hammond and Dale McAlpine - despite their homophobia - even offering to testify in their defence in court. I've also been involved in campaigns defending persecuted Christians in countries like Pakistan and Saudi Arabia.
We humanists believe that freedom of religion - and non-religion - is a fundamental human right.
Peter Tatchell is Director of the Peter Tatchell Foundation. For more information about his human rights work, to receive his campaign bulletins or to make a donation: PeterTatchellFoundation.org