WASHINGTON - Canada and the United States are not just two of the world's closest neighbours in terms of commerce, trade and culture, but the former British colonies also shared many of the same fundamental beliefs and ideals as they forged their respective nations.

How, then, did religion come to play such a significant and enduring role in public policy in the United States compared to its neighbour to the north?

Just over 67 per cent of those who participated in the 2011 National Household Survey — Statistics Canada's voluntary replacement for the cancelled mandatory long-form census — reported being "affiliated with a Christian religion," the agency reported Wednesday.

But among new Canadian immigrants, the number of Christians has dropped to 47.5 per cent from 78 per cent in 1971, while nearly one-quarter of the Canadian population reported having no religious affiliation at all, compared with 16 per cent in 2001.

In the U.S., meanwhile, the vast majority of Americans still consider themselves religious — many of them devoutly so.

A recent Gallup survey found that throughout the U.S. in 2012, 40 per cent of Americans considered themselves to be "very religious." Twenty-nine per cent described themselves as moderately religious, while 31 per cent said they were not religious.

Because Canadians tend to be more socially liberal than their southern neighbours, organized religion pays a greater price for those perceptions in Canada than in the U.S., experts say.

South of the border, by way of contrast, abortion — to name just one pet cause of the religious right — remains a hot-button issue as a host of state legislatures pass increasingly restrictive anti-abortion laws. Any prospect of that debate being reopened in Canada has been snuffed out by Prime Minister Stephen Harper.

There are myriad reasons for the divergent religious makeup of the U.S. and Canada, academics say.

They run the gamut from demographic and immigration trends to the religious beliefs of the founding fathers of both nations and each country's response to the profound social and cultural shifts of the 1960s.

African-Americans, making up 12 per cent of the U.S. population, are avid churchgoers. A 2009 Pew Research study found they surpass other Americans on a host of faith fronts, including praying more often and attending church more frequently.

Hispanics, the fastest growing demographic in the country and now more numerous than African-Americans at 15 per cent of the population, are also more religious than most Americans, although they're growing less so.

And unlike Canada, there remains a large swath of the United States — the South — that is staunchly religious as well as politically powerful. Only pockets of similarly devout believers are scattered throughout Canada, making it harder for them to shape public policy.

The Gallup study found that eight out of 10 of the most religious states in the union are in the South, with Alabama and Mississippi in the Top 3. Utah, with its substantial Mormon population, is No. 2.

Southerners evidently still agree with the founding fathers of the United States, who not only enshrined religious freedom in the Constitution, but also, critically, protected the public exercising of religion.

"Religion has always had a significant role in American public policy, right from Day 1," said Thomas Farr, former director of the U.S. State Department's religious freedom office.

The U.S. Constitution's First Amendment was "the first major sign of the religious nature of our founders and the nature of the country," said Farr, who's now the director of the Religious Freedom Project at the Berkley Center for Religion, Peace, and World Affairs in Washington.

"We wanted to protect the exercise of religion; not just religious beliefs, but the actual exercise of religion. Why? It was because they wanted it in public policy. Exercise is an active thing. They intended it to be more than just freedom of religion, they wanted people to be actively religious. That's why they wanted it protected and accommodated."

That wasn't the case in Canada, where the fathers of Confederation had to gingerly negotiate the often bitter religious animosities between the "two solitudes" — Protestant English Canada and Catholic French Canada. There was little appetite to allow religion to play a major role in determining public policy, no matter the personal religiosity of the Canadian founders.

"There was never the same impulse in Canada, understandably," Farr said.

Stuart Macdonald, a professor of church and society at Knox College at the University of Toronto, agreed.

"In Canada, you had to make peace between Catholics and Protestants," he said.

But Macdonald disputes the notion that Canada and the U.S. have always been vastly different in terms of religion and its impact on public policy, arguing the contrast is relatively recent and only truly took hold in the 1970s.

He points to a surprising figure as someone who galvanized the religious right at a time when Canada began to become secular — former U.S. president Jimmy Carter.

"In Canada, we were very close to the U.S. in terms of religion well into the early 1960s, and even after that our trends were very similar, so this is an awfully recent phenomenon," he said.

After the sexual and civil rights revolutions of the 1960s, citizens of both countries changed in terms of their religiosity, Macdonald said — but then came Carter, whose election in 1976 marked a milestone for evangelical Christians.

"There was this major culture shift, but then there was a rebound of religion in the United States around the time of the Carter presidency," he said.

"He ran as an evangelical Christian and he put religion right back in the spotlight in the U.S., whereas in Canada, Trudeau remained quiet about religion, even though he was personally religious."

The swiftness of the change in religious attitudes in Canada is paid short shrift, Macdonald adds, and doesn't necessarily suggest that the new normal will be a permanent state of affairs.

"In 1967, centennial year celebrations began with an all-Christian worship service, which we can't even imagine now," Macdonald said. "The Jewish representative wasn't even allowed to read anything. And that wasn't a very long time ago."

And does religion truly play less of a role in public policy in Canada than it does in the United States?

Don Hutchinson of the Evangelical Fellowship of Canada isn't so sure.

There's a long tradition in Canada of co-operation between the church and state in areas like education, health care and social welfare, he points out.

Hutchinson, the director of the organization's Centre for Faith and Public Life, says Canada's religious groups are more careful — indeed, more Canadian — about the language they use while attempting to influence public policy.

"In the U.S., there's still an openness to quoting the Bible as a stand-alone, reliable source as the position being taken on some issues," he said.

"In our culture, we have come to the conclusion that the language of public policy development is a language that we have to learn how to communicate .... In Canada, religious organizations have effectively engaged in public policy by identifying the principles we have found in our religious beliefs, assessing them and proposing sound public policy based on these beliefs by using a common language."

It's not that Canadian religious organizations are more clever than those in the U.S., he added with a laugh.

"We have different cultures, so we are politically attuned to communicating in our unique, polite Canadian environment."

Related on HuffPost:

Loading Slideshow...
  • The Survey

    CP — Statistics Canada released the first tranche of results Wednesday from the 2011 voluntary National Household Survey, which replaced the cancelled mandatory long-form census. The survey, which replaced the mandatory long-form census cancelled by the Harper Conservatives in 2010, is filled with warnings that the data may not be as accurate, given the survey's voluntary nature. HIGHLIGHTS:

  • Nation Of Immigrants

    Canada was home to an estimated 6,775,800 immigrants in 2011, comprising 20.6 per cent of the population — more than ever before and the highest proportion of all G8 countries.

  • Aboriginal Population Growth

    Canada's aboriginal population grew by 20.1 per cent — 232,385 people — between 2006 and 2011, compared with 5.2 per cent for non-aboriginal people. 1,400,685 people identified themselves as aboriginal in 2011, representing 4.3 per cent of the Canadian population. Aboriginal Peoples accounted for 3.8 per cent of the population in 2006, 3.3 per cent in 2001 and 2.8 per cent in 1996.

  • Foster Care

    Almost half (48.1 per cent) of all children aged 14 and under in foster care in Canada in 2011 were aboriginal children.

  • Aboriginal Children

    Aboriginal children aged 14 and under made up 28 per cent of Canada's total aboriginal population, while their non-aboriginal counterparts represented 16.5 per cent of all non-aboriginals.

  • Native Tongue

    Only 17.2 per cent of aboriginals reported being able to conduct a conversation in an aboriginal language, compared with 21 per cent in the 2006 census.

  • Foreign-Born

    About 1,162,900 foreign-born people immigrated to Canada between 2006 and 2011, making up 17.2 per cent of the foreign-born population and 3.5 per cent of Canada's total population.

  • Ethnic Origins

    More than 200 different ethnic origins were reported in the 2011 survey, with 13 of them representing more than a million people each.

  • Visible Minorities

    Nearly 6,264,800 people identified themselves as a visible minority, representing 19.1 per cent of the population. 65 per cent of them were born outside Canada.

  • Predominant Groups

    South Asians, Chinese and blacks accounted for 61.3 per cent of the visible minority population, followed by Filipinos, Latin Americans, Arabs, Southeast Asians, West Asians, Koreans and Japanese.

  • Religion

    More than 22.1 million people — two-thirds of Canadians — said they were affiliated with a Christian religion, including 12.7 million Roman Catholics, the largest single group.

  • No Religion

    7.8 million people, 23.9 per cent of the population, reported having no religious affiliation.

  • Slightly more than one million people, or 3.2 per cent of the population, identified themselves as Muslim, while Hindus represented 1.5 per cent, Sikhs 1.4 per cent, Buddhists 1.1 per cent and Jews one per cent.

  • NEXT: Highlights Of 2011 Census

  • Highlights Of The 2011 Census

    Here are some highlights from the 2011 Canadian Census. With files from <em>The Canadian Press</em>. (AFP/Getty Images)

  • 33,476,688 People

    As of May 2011, 33,476,688 people were enumerated in Canada, nearly twice as many as in 1961 and 10 times the number in 1861. (Alamy)

  • Population Growth Speeds Up

    Canada's population grew by 5.9 per cent between 2006 and 2011, up slightly from 5.4 per cent during the previous five years. (<a href="http://www.flickr.com/photos/jtbradford/" target="_hplink">Flickr: jtbradford</a>)

  • Go West

    For the first time, more people in Canada live west of Ontario (30.7 per cent) than in Quebec and Atlantic Canada combined (30.6 per cent). (Flickr: <a href="http://www.flickr.com/photos/derekgavey/" target="_hplink">derekGavey</a>)

  • We're Number One

    Canada's population growth between 2006 and 2011 was the highest among G8 countries. (<a href="http://www.flickr.com/photos/33498942@N04/" target="_hplink">Flickr: WarmSleepy</a>)

  • Exceptions To The Rule

    Every province and most territories saw their population increase between 2006 and 2011; the rate of growth increased everywhere except in Ontario, the Northwest Territories and Nunavut. (AP)

  • Ontario Falters

    The growth rate in Ontario declined to 5.7 per cent, its lowest level since the early 1980s. (Alamy)

  • Saskatchewan Out Of The Red

    Population growth in Saskatchewan hit 6.7 per cent, compared with a negative growth rate of 1.1 per cent between 2001 and 2006; the province welcomed more than 28,000 immigrants during the latest census period, nearly three times the number of the previous five-year period. (<a href="http://www.flickr.com/photos/justaprairieboy/" target="_hplink">Flickr: Just a Prairie Boy</a>)

  • Yukon And Manitoba Take Off

    The rate of growth in both Yukon (11.6 per cent) and Manitoba (5.2 per cent) has doubled since 2006. (<a href="http://www.flickr.com/photos/us_mission_canada/" target="_hplink">Flickr: US Mission Canada</a>)

  • The East Is Growing Too

    The rate of growth in Prince Edward Island (3.2 per cent), New Brunswick (2.9 per cent) and Newfoundland and Labrador (1.8 per cent) has increased substantially between 2006 and 2011. (<a href="http://www.flickr.com/photos/jw1697/" target="_hplink">Flickr JaimeW</a>)

  • Cities Rule..

    Nearly seven of every 10 Canadians lived in one of Canada's 33 main urban centres in 2011. (<a href="http://www.flickr.com/photos/markwoodbury" target="_hplink">Flickr mark.woodbury</a>)

  • .. Except Not In Ontario..

    The rate of population growth in almost all census metropolitan areas located in Ontario slowed between 2006 and 2011. (<a href="http://www.flickr.com/photos/husseinabdallah/" target="_hplink">Flickr abdallahh</a>)

  • Maybe Because Everyone Moved To Alberta

    Of the 15 Canadian communities with the highest rates of growth, 10 were located in Alberta. (AFP/Getty Images)