January 20, 1983

The gross national product, the broadest measure of the nation's economy, declined at an annual rate of 2.5 percent in the final three months of last year, the Commerce Department reported today. For 1982 as a whole, it fell 1.8 percent, the sharpest year-to-year decline since 1946. The department attributed much of the fourth-quarter decline in the G.N.P., which measures the total value of goods and services, to a drop in exports and to manufacturers who slowed production and cut inventories in the face of discouraging sales. These declines offset rises in consumer spending and housing.

Could the recovery turn out to be appreciably stronger than almost everyone expects? It has happened before. Although predictions for an anemic recovery still predominate, some economists foresee a somewhat snappier comeback. ''I think people are going to be surprised about the strength of the recovery as we move through the year,'' said Edward Guay, chief economist for the Cigna Corporation, the insurance company. He predicted that real gross national product in the fourth quarter of 1983 will be 5.8 percent higher than in the last quarter of 1982, and that industrial production will be 8 percent higher. He said that average annual real G.N.P. in 1983 will be 3.6 percent above 1982. ''Forecasters, by and large, have usually underestimated the speed of recovery once it gets started,'' stated Edgar R. Fiedler, vice president for economic research at the Conference Board. ''It is often hard to see the sources of strength. But once they get started, they tend to cumulate even faster than expected.''

Mayor Koch chose a celebration at a West Side synagogue last night to complain that, among religious institutions providing beds for New York City's homeless population, ''there is not a single synagogue.'' ''We all know that the Jewish community could be doing more to fulfill its responsibility to the quality of life in New York,'' the Mayor said in a speech honoring the 75th anniversary of the Stephen Wise Free Synagogue, 30 West 68th Street. He then renewed his recent theme that a troubling selfishness afflicts city neighborhoods. To a crowd of 300 in the synagogue's basement meeting room, Mr. Koch conceded that joining in the city's program to care for thousands of homeless people in armories and city-run shelters could be troublesome for private groups such as churches and synagogues. Besides, he said, synagogues already do ''a lot of important social work.'' But none of it, he said, is the same as ''providing a bed.''

WHEN Angelo Rafael Donghia arrived in New York in 1959, the decorating world still basked in the light of the pink silk lamp shade. Elsie de Wolfe and Syrie Maugham were decorating deities. Billy Baldwin was king. Arrayed beneath them, a small, select hierarchy led by Sister Parish, Dorothy Draper and Eleanor Brown ordered swags for the small, rich hierarchy of New York, Los Angeles, Chicago and Palm Beach. The world had not yet been exposed to high tech or designer sheets. Although there were outposts of decorators in a few major American cities, the upholstered heart of that world was in Manhattan, where most young decorators wore navy blazers and did their own laundry. ''And almost no one made any money,'' said Mr. Donghia recently as he leaned back in a gray flannel chair in his gray flannel office. Profit, in those days, seemed oddly beside the point, if not impossible. Unless, that is, one happened to be Angelo Donghia. Like many other young decorators in town, his first job paid $75 a week.His apartment cost $60 a month. He had one good pair of tasseled loafers.

Two of the nation's largest banking organizations, the BankAmerica Corporation of San Francisco and the Continental Illinois Corporation of Chicago, yesterday reported sharp declines in fourth-quarter operating earnings. At BankAmerica, the nation's second-largest bank holding company after Citicorp, earnings before securities transactions dropped 13.2 percent, to $73.4 million, but the decline would have been much steeper if it had not been for a nonrecurring factor that bolstered the quarter's income by $30.8 million. Without that factor, the company's earnings would have declined by 50 percent, from the $84.6 million earned in the fourth quarter of 1981. On a per-share basis, operating earnings, before securities gains and losses, dropped to 46 cents, from 57 cents, the company said.