Cardinal Francis George of Chicago (pictured), has come out in defence of fast food chain Chick-fil-A, after the company was condemned by the mayors of Boston, Chicago and San Francisco because its owner supports traditional marriage.

The owner of the chain, Mr Dan Cathy was asked about same-sex marriage and he reiterated his support for the traditional understanding of marriage.  

In response, the mayors of Boston, Chicago and San Francisco condemned the fast food retailer. Chicago mayor, former chief of staff to President Obama, Rahm Emanuel, said that the chain’s values “are not Chicago’s values”.

The mayor of Boston said he would deny the retailer a permit in his city given the chance.

Responding to the attacks on Mr Cathy, Cardinal George said: “Approval of state-sponsored homosexual unions has very quickly become a litmus test for bigotry; and espousing the understanding of marriage that has prevailed among all peoples throughout human history is now, supposedly, outside the American consensus.  

“Are Americans so exceptional that we are free to define “marriage” (or other institutions we did not invent) at will? What are we re-defining?”

He pointed out that neither Church nor state invented marriage, “and neither can change its nature”.  

He said: “Marriage exists because human nature comes in two complementary sexes: male and female. The sexual union of a man and woman is called the marital act because the two become physically one in a way that is impossible between two men or two women.  

“Whatever a homosexual union might be or represent, it is not physically marital. Gender is inextricably bound up with physical sexual identity; and “gender-free marriage” is a contradiction in terms, like a square circle.”

In a radio interview some weeks ago, Mr Cathy said: “I think we are inviting God’s judgment on our nation when we shake our fist at (God) and say, ‘We know better than You what constitutes a marriage.’

“I pray God’s mercy on our generation that has such a prideful, arrogant attitude to think we would have the audacity to redefine what marriage is all about,” he said.

The words ignited a storm of criticism. Boston Mayor Thomas Menino said: “Chick-fil-A doesn’t belong in Boston,” he said. “We’re an open city. We’re a city at the forefront of inclusion.”

He added: “Because of (Dan Cathy’s) ignorance, I will deny Chick-fil-A a permit to open a restaurant in my ward,” said.

New York City Council Speaker Christine Quinn called upon New York University to kick Chick-fil-A off its campus.

However, New York Mayor Michael Bloomberg, an ardent supporter of same-sex marriage, said he disagreed with his fellow mayors on the issue of whether Chick-fill-A should be allowed into their cities.

Mr Bloomberg said: “You can’t have a test for what the owner’s personal views are before you decide to give a permit to do something in the city.”

Richard Socarides, a New York lawyer who is urging a boycott of Chick-fil-A, agreed with Mr Bloomberg.

“Consumers can disagree with a company’s corporate political position and decide not to spend money there,” Socarides said. “But the city cannot regulate speech by denying someone a permit to operate their business just because you disagree with their political beliefs.”

Mr Menino has more recently said he was expressing his own opinion and acknowledged there is little he can do to prevent the chain from coming to Boston.

A spokeswoman for Mr Emanuel said that while the Chicago mayor believes that Cathy does not share his city’s values, he would not block Chick-fil-A from opening a new restaurant.