Lord Mackay of Clashfern has argued that Christians must be free to act on their consciences when it comes to gay rights.
The former Lord Chancellor under Margaret Thatcher and John Mayor said insisting that Christians abide by equality laws – such as in the case of hotel owners – was “Orwellian”.
Last month, gay couple Martin Hall and Steven Preddy won their case against a Christian-run bed and breakfast which barred them from sharing a room.
A judge ruled that the gay couple, who are in a civil partnership, should have been treated in the same way as a heterosexual married couple as the 2007 Sexual Orientation Regulations state.
Writing for ConservativeHome, Lord Mackay, who has frequently voted against gay rights, argued: “Most people still affectionately regard marriage, as understood by English law and the Church, as deserving of its special status.
“To equate civil partnerships with marriage is a big step to take. For the law to force people to equate the two, and penalise those who do not, is an Orwellian leap.”
Supporters of Mr Hall and Mr Preddy argued that Peter and Hazelmary Bull were not forced to run a bed and breakfast and that they were not expected to open up the private areas of their home, such as their bedroom, to guests.
Lord Mackay wrote: “Yes, but the right to liberty of conscience, freedom of expression and religious liberty is not restricted to the private realm.
“One does not lose them when one steps into the public sphere. Indeed, for the sake of everyone’s liberty it is paramount that such rights are upheld in the public realm.
“Consider an atheist who seeks to work as a teacher in a state school in full knowledge that the law requires a daily act of religious worship. Do we say his beliefs should be left at home? Do we say he has stepped into the public sphere and his personal views ought not be accommodated?
“No, the law allows liberty of conscience. A Christian deserves the same.”
In August, Lord Mackay called on Scottish courts to be sent Bibles so they could take God’s word into account when administering justice.
The National Secular Society asked if this would include killing gay people and adulterers.
Mr and Mrs Bull were given leave to appeal the judge’s ruling.
Last week, it was reported that another gay couple are suing a hotel which barred them from sharing a room.
Michael Black, 63, and John Morgan, 58, have begun legal proceedings against the Swiss B&B in Berkshire, after owners Susanne and Mike Wilkinson denied them a double room last March.