This is the year of decision in Canada's most serious identity crisis in more than a century.

With the prospect of Quebec secession looming large over other issues, a general election in May will revolve largely- around Pierre Trudeau's 11-year effort as prime minister to keep English Canada and French Canada together in on country.

Opposition Conservative leader Joe Clark has accused Trudeau of having divided Canada as never before, but Clark has yet to spell out in detail his own vision of the country's future.

The crucial test, however, will take place in the predominantly French-speaking province of Quebec probably in the fall-when the separatist government of Premier Rene Levesque holds a referendum on sovereignty holds a referendum on sovereignty. Latest polls indicate that about one-half of the Quebec population favors an independent Quebec in economic association with the rest of Canada.

The two electoral tests will climax a long and traumatic public debate on Canadian unity that was ignited by a stunning victory of Levesque separatist Parti Quebecois in the October 1976 provincial elections.

Ever since, Canadian preoccupation with an uncertain furture and the wide-spread anxieties it breeds have sapped a disproportionate amount of national energy. It also has forced Canadians to search their souls as to what kind of country they want.

The marriage of English-speaking and Francophone Canada has long gone sour, yet there are conflicting views whether it is beyond repair.

In this atmosphere of smoldering tenstion, however, when one partner talks of divorce and the other wants to repair the relationship, one thing seems clear: While Canada may yet survive as a united country, it would be an illusion to believe that the current constitutional arrangements could survive intact.

English-speaking Canadians appear fatalistic. The more serious the secessionist trend has been revealed to be in recent Quebec polls, the more determined English Canada seems to ignore it. "They won't do it," is the staple answer.

But what if Quebec decides to go on its own? "We'll joint the United States," one person in Toronto responded bluntly. "I wouldn't mind being an American.

Sampling opinions at a more sophisticated level, the same question elicits similar responses.

"There can be no separation," john Saywell, a prominent historian and professor at Toronto's York University, said. "Even if Levesque wins the referendum, nobody will negotiate with him. Under the constitution, they cannot proclaim independence, so nothing will ahppen."

Toronto's business community is hedging its bets, however, Illuminating is a Toronto manhs plan to purchase a large mansion in downtown Montreal. Many well-to-do English-speaking Montrealers have moved away since Levesque took power, and the exodus has repressed real estate prices here.

A similar mansion in Toronto would cost four times as much, the man said. "If Levesque wins in the referendum, the building would be perfect for the embassy of a medium-sized country. If not, the prices are going to go up again."

Here in the heart of French Canada, however, the mood is one of hope and and anxiety. While yearning for acknowledgment of Quebec nationality, many in Quebec have lingering doubts about the price they would have to pay if Levesque wins the referendum.

"My heart says yes, my head is not so sure," said Hugues Letourneau, 24, a native of Montreal. "Morally I feel I should vote for independence, but I just don't know."

The undercurrent of Quebec nationalism has existed here for a long time, although initially it was merely an instinct ot make connections with the French past from which Quebec had been cut off after Wolfe defeated Montcalm on the Plains of Abraham in 1759.

But one senses while viewing the deeply rooted French life in Quebec -- which seems different from English Canada's shallower and looser growth -- that the French connection now is incidental and taht Quebec belong to the Canadian tradition, and the Canadian way of tetting things done is quite distinct from the American way. It is quietr, more orderly, less vdilent.

Perhaps because of this tradition of reasonableness and civility, revolutionary changes are taking place in Quebec but they are so undemonstrative or low key that a visitor has to search for them.

For the first time in more than two centuries, a well-educated, youthful-French-speaking intellectual elite is in charge of the province, using all at its disposal to ensure the continued existence of the Quebec nation.

"In economic terms, there are still reservations about whether an independent Quebec would be viable," said Jean Gerin-Lajoie, leader of the Quebec steelworkers. He and his 45,000-strong union support Levesque.

"But we have to pull ourselves up by the bootstraps and this includes political independence. Our economic vitality depends on independence. Otherwise we shall disappear because our existence would become futile."

While yough, unionized labor and interllectualls support Levesque, French businessman, some professional people and older persons are weary of independence.

"Independence is a good thing except that its cost would be high," an elderly Montreal resident said, reflecting the views of many here.

Challenging Levesque's separatists for provinical leadership is Claude Ryan, a suave former newspaper editor, who maintains that Quebec can get the political power it seeks with the breaking up the Canadian federation.

Clearly more at home in the realm of ideas than the rhetorie of political struggle, Ryan has been unable to define his positions in a way to be distinct from Levesque's and still appeal to Quebec nationalists.

"The room of diversity must remain the cornerstone of Canda," he says. The people of Quebec, he believes, "want to have as much room as is compatible with the federal Canada." Thus the program of Ryan's Liberal Party calls for greater power for Canada's 10 provinces, constitutional arrangement that would give Quebec speical status, including the right to maintain international relations, and safeguards against excessive use of federal powers.

Lost in the rhetoric of the debate, however, is the fact that virtually the entire French-speaking population is united behind two similar platforms that demand drastic constitutional changes between Ottawa and the 10 provincial governments.

Also lost in the debate is the prevailing view tht most of the measures the Levesque government has adopted during the past two years, includint the one that makes French the language of Quebec, could not be reversed.

As Tim Creery, the editor of the Montreal-based magazine Report put it, "A number of things have occurred or are occuring which people thought were obtainable only under sovereignty."

Against the Parti Quebecois victory in 1976 was a landmark event in Canadian history, serving as it did as the catalyst in the evolution of an entirely new Canadian constitutional arrangement.

What is at stake here today is not so much a realignment of federal-provincial rights. Rather it is the will of an unknown number of people in Quebec to be internationally recognized as a sovereign nation.

This, by and large, is an emotional question.