Christians and other faith groups should have a conscience clause enshrined in law within a Bill of Rights as a way of protecting fundamental rights, an independent think tank has advised.

The paper, by influential conservative-leaning think tank ResPublica, suggests that the current focus on rights and equality erodes diversity, rather than fostering it, imposing “uniform and unwelcome conformity” on society at large and religious minorities in particular.

It urges the Conservative government to uphold a manifesto pledge to scrap the Human Rights Act and replace it with a Bill of Rights as a way to protect the freedom of religious belief.

Instead of setting out a list of competing rights, as the Human Rights Act does, the Bill of Rights would place a duty on employers and others to make a “reasonable accommodation” for religious belief, the report suggests.

It follows a string of cases in which the rights of Christians to practice their religion has been set against others’ rights.

In the most recent high-profile case, the Court of Appeal in Belfast upheld a ruling which found that the owners of Asher’s Baking Company had discriminated against a gay rights activist for refusing to bake a cake bearing the political slogan “Support Gay Marriage”. The case is set to go to the Supreme Court.

But the report points out that freedom of religion is not a “niche” issue.

“Evidence demonstrates that societies that vigorously protect religious freedom enjoy a wide range of other fundamental rights as well, in particular freedom of speech and freedom of association. Religious freedom remains one of the most effective limits on the intrusion by the state on individual and communal life,” a spokesman for the think tank said.

Phillip Blond, director of ResPublica, added: “We hear a lot about the bad things people do in the name of religion but all faiths actually have a role to play in bringing communities together and stopping division.

“Those who go to church, temple or mosque are far more likely to act in the public good whether it is helping deliver meals on wheels or running toddler clubs, or simply being part of a group of like-minded people.”

The report comes days after the chairman of the Equality and Human Rights Commission (EHRC), David Isaac, called for a “common sense approach” in dealing with religion at work.

“Freedom of religion is a fundamental human right and it shouldn’t be suppressed through fear of offending. Lots of employers have now become really worried about doing anything discriminatory regarding their Muslim or Jewish staff,” he told the Sunday Times.

He added, “It is OK to hold a [Christmas] party and to send Christmas cards.”

His comments were raised at Prime Minister’s Questions on Wednesday by Conservative MP Fiona Bruce.

“Many Christians are now worried, even fearful about mentioning their faith in public,” she told Theresa May.

May, the daughter of a vicar, agreed saying: “We’re now into Advent, and we have a very strong tradition in this country of religious tolerance and freedom of speech.” She added: “Our Christian heritage is something we can all be proud of.

“We all want to ensure that people at work do feel able to speak about their faith and also feel able to speak quite freely about Christmas.”