The Government's gay marriage proposals do not go far enough, according to a poll of the lesbian, gay, bisexual and transgender (LGBT) community.
The controversial introduction of same-sex marriage will be put to a Commons vote next week.
But in a survey, six out of 10 gay people said the Government's plans would not create "equal marriage", and that equality would only be achieved when churches, synagogues and mosques are required to carry out same-sex weddings.
The poll found that half of all LGBT people expect the courts to remove the remaining protections on places of worship.
Nearly two-thirds (62%) believed Prime Minister David Cameron was trying to extend marriage to LGBT people to make the Tories look more compassionate rather than because of his convictions.
The poll - which questioned more than 500 LGBT people - was commissioned by the Coalition for Marriage - an alliance of groups and individuals opposed to attempts to redefine marriage.
The organisation's campaign director Colin Hart described the results as a "wake-up call to the Government".
He said: "These poll results should be a real eye opener for David Cameron. They show that the PM's motives are not trusted. Just 15% of LGBT people believe his claims that he is making the change out of conviction.
"They also show that Mr Cameron's plans to force this Bill through Parliament with little or no debate is not supported even by those who back the change, because they fear this might do more harm than good.
"So when will the Government listen to the growing number of MPs, peers, legal and constitution experts who are saying that this legislation will have all sorts of unintended consequences?
"Ordinary people - teachers, parents, foster carers and those who work in the public sector - who back the traditional definition of marriage face being treated like outcasts, disciplined or sacked from their jobs.
"Mr Cameron should either ditch this unpopular and unworkable legislation, or at the very least put it before the British public."