Canada will become the third country in the world to officially sanction same-sex marriage.

In a 158 to 133 vote, the House of Commons adopted Bill C-38 -- the controversial legislation legalizing same-sex marriage from coast to coast -- on its third and final reading Tuesday night.

The Liberals had the support of almost all New Democrat and Bloc Quebecois MPs for the vote.

The bill will become official once it receives Senate approval, which is expected by the end of July. An earlier Conservative motion to send the bill back to committee was voted down 158 to 127.

"(This) is about the Charter of Rights,'' Prime Minister Paul Martin said earlier Tuesday.

"We are a nation of minorities. And in a nation of minorities, it is important that you don't cherry-pick rights.

"A right is a right and that is what this vote tonight is all about."

The decision marks the end of a long and divisive debate, with fierce opposition coming from Conservative members, religious groups, and even members of the Liberal Party.

The legislation applies to civic weddings at public venues like city halls and courthouses. Religious groups still have the right of refusal to sanctify same-sex marriages, but opponents of the bill are vowing to keep up their fight -- fearing they could be sued for refusing to carry out same-sex marriages.

"(This) is effectively exposing people of faith to persecution and prosecution," said Charles McVety, president of the Canada Family Action Coalition. "I want to make it very clear today that this is the beginning of the formal fight against the definition of marriage."

Conservative Leader Stephen Harper, meanwhile, is promising that he won't let the issue rest. He says he'll bring back the same-sex marriage law for another vote if he becomes prime minister.

"There will be a chance to revisit this in a future Parliament," Harper said. "Our intention is to have a free vote."

He also repeated his claim that the law lacks legitimacy because it passed with the support of the separatist Bloc party.

"I don't think Canadians are going to accept as a final word a decision taken by only a minority of federalist MPs," he said. But Harper didn't specify how he would address the issue if the Tories were to form the next government.

Liberal Justice Minister Irwin Cotler said Harper is going to have to come clean and acknowledge that he would have to invoke the Constitution's notwithstanding clause to override the new law.

"They're going to have to acknowledge that they want to override the (Charter of Rights); override constitutional-law decisions in nine jurisdictions in this country; override a unanimous decision of the Supreme Court of Canada; override the rule of law in this country," Cotler said.

The clause is available to provinces to override federal laws that
intrude on provincial jurisdiction.

But almost every provincial and territorial government has legalized same-sex marriage; and the new legislation will ensure that four "hold-out" jurisdictions -- Alberta, Prince Edward Island, Nunavut and the Northwest Territories -- must now strike down their traditional marriage laws.

"It's an historic moment, it's about equality for gays and lesbians," said NDP MP Libby Davies.

Alberta Premier Ralph Klein, who's "strongly opposed" to the bill on moral grounds, acknowledged Tuesday that little can be done now to stop same-sex marriages in his province.

"Since this is federal legislation, to use the notwithstanding clause as contained in our own Marriage Act would be frivolous," Klein told reporters in Calgary. "It wouldn't stand up in any court of law. So there are some other options that we would have to consider."

Klein said although some members of his caucus are threatening to use everything at their disposal to get around the legislation, "there are no legal weapons; there's nothing left in the arsenal."

As expected, about three dozen Liberal MPs voted against the bill. Martin declared it a free vote for backbench MPs, but cabinet ministers were under orders to vote in favour of the bill.

That prompted a junior cabinet minister to resign and return to the backbenches rather than vote in favour of same sex marriage.

Joe Comuzzi, the minister of state for economic development in northern Ontario, informed the prime minister of his decision in the early morning.

"I promised faithfully to the people of Thunder Bay-Superior North that I would defend the traditional definition of marriage," he explained to reporters on Parliament Hill.

After the same-sex vote was put to bed, the House immediately adjourned for the summer, thus ending one of the stormiest sessions of parliament in Canadian history.

MPs won't meet again until Sept. 26.

With a report from CTV News