What was going on when I was born?

The Beirut massacre has plunged Israel into moral turmoil. To many Israelis, the old foundations of right and wrong feel shaken loose. A sudden wilderness seems to have enveloped the nation. There is no voice to speak for its conscience. ''I'm afraid that I don't know this country anymore,'' said an officer in the army reserves. ''They are destroying my country,'' said a woman in Jerusalem who fought to establish the state in the 1940's. Against this void, a search has begun for some equilibrium in which to examine the moral questions, to define the scope and limits of Israeli responsibility for the slaughter of hundreds of Palestinian men, women and children last week by Lebanese Christian forces. With a Government that apparently does not want independent questioning, it has fallen to each individual, each circle of friends and the larger circle of the nation. Step by step the picture is being assembled as soldiers come forward and the Israeli press probes.

Amin Gemayel took office as President today and pledged to work toward transforming Lebanon ''into a new, dynamic country'' free of foreign troops and of the long ''vicious cycle of bloody violence'' that it has suffered. The new President, a 40-year-old Maronite Christian lawyer and Member of Parliament, also made a gesture to Lebanon's Moslem leaders, pledging to maintain the nation's ties to the Arab countries, which he referred to as ''our Arab brothers.'' ''We have great hopes for him,'' former Prime Minister Saeb Salam, an influential Moslem leader, said of the new President. Israeli Pullout Goes On Elected two days ago by Parliament with strong support from Moslems, Amin Gemayel replaced his younger brother, Bashir, who became President-elect on Aug. 23 and was assassinated nine days ago. Amin Gemayel was sworn in today for a six-year-term, succeeding President Elias Sarkis.

''I offer no program for a new era because a single concern grips us now.

An article in Metropolitan Report Monday incorrectly identified the net- work affiliation of WKBW television in Buffalo. It is affiliated with ABC.

''THE show is actually a joke, a play on words,'' Steve Allen said the other night between shows. ''A few years ago somebody asked me, 'Have you seen ''Jacques Brel Is Alive and Well''?' and I answered, 'No, but I've seen ''Seymour Glick Is Alive but Sick.'' ' '' And so Mr. Allen, a restless, darting talent who seems to compose songs, conduct orchestras, write books, do standup comedy and create television and radio scripts between lecture and concert tours and acting assignments, whipped up a comic musical revue that riffles through the somewhat checkered existence of Seymour Glick, who emerges as the quintessential show business hanger-on. The revue provides the 61-year-old Mr. Allen with a vehicle to display several of his talents - song and comedy writing as well as the offhand quip.

Consumer prices rose just 0.3 percent in August, the Labor Department reported. The figure indicated that the inflation rate for the year could slow to 5.5 percent or below, the lowest level in six years and less than half that of 1979 and 1980. For the year so far, the Consumer Price Index is up at an annual rate of 5.1 percent. Treasury Secretary Donald T. Regan hailed the new data as evidence that recovery was near. (Page A1.) Prices in the New York area rose 0.5 percent. (D3.) The Senate killed a bill that would have let investors take a longterm capital gains tax break on profits from securities and other assets held for six months. (D1.)

The Allied Corporation is negotiating a truce with the Martin Marietta Corporation that would guarantee the independence of the big aerospace company, Wall Street sources said yesterday. The truce would break a stalemate between Marietta and the Bendix Corporation, each of which is attempting to take over the other, and thus clear the way for Allied to proceed with its own plan to acquire Bendix. Marietta was understood to have decided to negotiate with Allied after a decision by the Delaware Chancery Court Wednesday night weakened Marietta's position. The ruling prohibits Marietta from voting any of the Bendix stock that it has acquired, thus preventing Marietta from exercising control over Bendix, even if, as expected, it buys more than 50 percent of Bendix's shares. The highly complex agreement under which Allied would acquire Bendix - an agreement still subject to change - went before the Allied and Bendix boards late yesterday for approval.

New car sales by the nation's three largest auto makers rose 16.5 percent in the mid-September selling period, the Big Three reported today. It was the first year-to-year rise reported since the eight-tenths of 1 percent increase reported for the June 1-10 selling period. Analysts attributed the unexpected strength in part to the dealer incentive programs ended recently and in part to returning consumer confidence.

Building service employees and apartment house owners in the Bronx reached a tentative agreement on a new contract yesterday, four days after the start of a walkout that affected 250,000 tenants in 2,000 buildings. John J. Kreidler, a state mediator, said union leaders had agreed to recommend the proposed agreement to members at a meeting tomorrow. Details of the tentative pact were withheld pending a ratification vote by the membership.

An acting justice in State Supreme Court in Brooklyn yesterday authorized an abortion to be performed on profoundly retarded 25-year-old woman after accepting the consent of her parents as a substitute for the consent of their daughter. The ruling, by Judge William J. Deeley, came two weeks after he had denied an abortion for the woman on the ground that the state had "woefully" failed to prove that her pregnancy was a threat to her life. Judge Deeley authorized the abortion to proceed, and the woman was admitted to a hospital last night, with the abortion scheduled for tomorrow. Believed to Be First of Kind "I don't want my daughter to suffer anymore than she has," the woman's father said after the court ruled on his consent. "I think I've done the best thing I could do for her."

A plan by A.T.& T. to push into the international telecommunications market has helped cause a rift between Philips, the giant Dutch electronics group, and the French electronics industry. Under an agreement announced Wednesday, the American Telephone and Telegraph Company would gain access to Philips's worldwide distribution network in exchange for the American company's technology. The two companies hope to sign the agreement by the end of the year, a Philips spokesman said. The agreement would provide initially for joint production and sales of digital switching equipment outside the United States. Such a pact would mark the first significant international venture for A.T.& T. and its telephone manufacturing subsidiary, Western Electric. Since the 1920's, A.T.& T. has confined its activities to the United States market. However, following the Reagan Administration's decision to drop antitrust proceedings against the company in exchange for the reorganization of its domestic subsidaries, Bell has made it clear that it plans to expand abroad.

Consumer prices rose only three-tenths of 1 percent in August, the Labor Department reported today. The figure indicated that the inflation rate for the year could slow to the lowest level in six years and less than half the double-digit pace of 1979 and 1980. In a special White House briefing called later in the day, apparently to emphasize the news, Treasury Secretary Donald T. Regan said, ''This is one more stake in the heart of the inflationary expectations.'' He declared: ''I believe these new figures show we're on the road to a sound recovery. Coupled with a continuation of slow, steady growth in the money supply, the result should be lower interest rates.''