British Christians do not think religion should have a special influence on public policy and display low levels of belief and practice, research suggests.
Despite identifying themselves with the religion, most turn out to be overwhelmingly secular in their attitudes on issues ranging from gay rights to religion in public life, the Ipsos Mori poll found.
Almost three quarters (74%) agreed that religion should not influence public policy, while only about one in eight (12%) thought it should, the survey found.
Conducted for the Richard Dawkins Foundation for Reason and Science (UK), it also found that 92% of Christians agreed the law should apply to everyone equally, regardless of their personal religious beliefs.
Six in 10 respondents (61%) agreed that homosexuals should have the same legal rights in all aspects of their lives as heterosexuals, and those who disapproved of sexual relations between two adults of the same sex (29%) were greatly outnumbered by those who did not (46%).
Less than a quarter of Christians (23%) believed that sex between a man and a woman was only acceptable within marriage.
The findings have been published after the Christian owners of a guesthouse who refused to allow a gay couple to stay in a double-bedded room lost an appeal over a ruling that they discriminated against the men.
In another victory for secularists last week, a High Court judge decided to outlaw the centuries-old tradition of formal prayers being said at the start of local council meetings.
The National Secular Society welcomed the rulings, saying there was no longer a "respectable argument" that Britain was a solely Christian nation, or even a religious one.
The Ipsos Mori poll, conducted among people who said they would be listed as Christians in the latest census, found more opposed than supported the idea of the UK having an official state religion, with nearly half (46%) against and around a third (32%) in favour.
The same pattern was repeated with the question of seats being reserved for Church of England bishops in the House of Lords, which 32% of respondents opposed and 25% supported.
More Christians opposed (38%) than supported (31%) the teaching of six-day creationism in state-funded school science lessons.
The current law in England and Wales requiring state schools to hold a daily act of broadly Christian worship was not strongly supported either, with almost as many Christians opposing it (36%) as in favour (39%).
Meanwhile there was strong support for a woman's right to have an abortion within the legal time limit, with more than three in five (62%) in favour and only one in five (20%) against.
Demonstrating an apparently weak faith, just over a quarter (26%) said they completely believed in the power of prayer, with more than one in five (21%) saying they either did not really believe in it or did not believe in it at all.
Almost half (49%) had not attended a church service in the previous 12 months, apart from on occasions such as weddings, funerals and baptisms.
Some 16% had not attended for more than 10 years, and a further 12% had never attended at all.
The research also found that at the time of the 2011 census, just over half (54%) of the public thought of themselves as Christian, compared with almost three-quarters (72%) in the 2001 census.
Welcoming the findings, Professor Richard Dawkins said: "In recent years Christian campaign groups have become increasingly vocal.
"Whether demanding special rights for Christians to be exempted from equalities legislation, strenuously opposing all attempts to review the law on assisted suicide, or campaigning against further social advances such as equal rights for gay people to marry, it is now clear that they are completely out of step not just with the population as a whole, but also with a significant majority of Christians.
"Britain is a secular society, with secular, humane values. There is overwhelming support for these values, even among those who think of themselves as Christian.
"Just as importantly, there is also deep opposition to the state promoting religion in our society. When even Christians overwhelmingly oppose the intermingling of religion and state policy, it is clearly time for the government to stop 'doing God'."
The results also showed that religion was "largely irrelevant even to those who still label themselves Christian", he added.
"When it comes to belief, practice or even the most elementary knowledge of the Bible, it is clear that faith is a spent force in the UK, and it is time our policy-makers woke up to that reality and stopped trying to impose beliefs on society that society itself has largely rejected," he said.