Israel's parliament, in a raucous emergency session with strong election campaign undertones, today easily defeated an opposition Labor Party motion condemning Prime Minister Menachem Begin's secret defense commitments to Christian militias in central Lebanon.

Amid almost constant heckling from the floor, Begin defended a pledge he made the Christians in August 1978 and reaffirmed in April, to use the Israeli Air Force to intervene if the Lebanese Christians came under attack by the Syrian Air Force. On April 28, Israeli jets shot down two Syrian helicopters used in support of Syrian attacks on the Christians in the Mount Lebanon range, and the Syrians responded by deploying surface-to-air missiles in Lebanon.

Begin said the agreement was not an abuse of his authority, as charged by the Labor Party, but had originally been endorsed by then foreign minister Moshe Dayan and then defense minister Ezar Weizman. He said the reaffirmation was backed by the Cabinet's committee on defense and security.

The Labor Party has been cautious in its statements on the Syrian missile crisis, limiting itself to allegations of mismanagement by Begin out of fear of appearing to be unpatriotic at a time of conflict with a bordering Arab state.

Former prime minister Yitzhak Rabin, leading the debate for the opposition, said the commitment to the Christians was unprecedented and gave a foreign party the power to decide when the Israeli armed forces should be used. No single leader of a democratic state has authority to enter such a military alliance without approval of the legislature, Rabin said.

The debate, at times, was drowned out by heckling. At one point, Labor's Micha Harish stood up and shouted at Begin, "You're lying to the Knesset [parliament]!" as pandemonium erupted on the floor.

The condemnation motion was defeated, 52 to 36, with four abstentions, including Dayan, who is heading his own party in the June 30 election.

In a separate debate, Begin renewed his attacks on West German Chancellor Helmut Schmidt for supporting Palestinian self-determination. Begin said Schmidt, who was a lieutenant in the Wermacht, "personally swore allegiance" to Adolf Hitler and kept his oath to the end of the war. Moreover, Begin added, all Germany shared the guilt for the Holocaust, and West Germany's reparations were only a fraction of what German's stole from Jews.