Israeli Prime Minister Menachem Begin and the Moral Majority's Rev. Jerry Falwell, in a bit of summitry that confounds even some of the truest believers, renewed their theo-political alliance yesterday and vowed to stand united against those who want to divide them.

The hour-long session at Blair House was the third such meeting of the two devoutly conservative leaders since they acceded to power in their respective constituencies. When they finished, they described separately to reporters how well it had gone.

"He told me, 'Reverend Falwell, there are those who are working very hard to separate us. But we are not going to be separated . . . . ' He said, 'There is a special relationship with Christians and Jews that is very dear to me,' " Falwell recounted.

"All proclaimed . . . to the city and the world they are friends of Israel," Begin said. "They are sincere and devoted friends. We are very grateful to them. They have proved it.

"There are some who object to this. But if a man or group will stretch out his hand and say 'I am a friend of Israel,' I will say, 'Israel has very strong enemies and needs friends.' Reverend Falwell is a very strong friend."

As Begin has said, any friend is welcome in these times of controversy and criticism of military actions Israel says it has taken in the name of self-defense.

Begin also is using Falwell as a sort of ambassador extraordinary and plenipotentiary to plead Israel's case to this nation's Christian fundamentalists, many of whom have never been considered personally fond of Jews and might well be presumed to have grown disenchanted with Begin's hard-line policies.

Begin had telephoned Falwell after Israel bombed the Osirak nuclear reactor in Iraq June 7. He asked for help in persuading Falwell's constituency that Israel had acted only defensively. Falwell subsequently preached that word.

For Falwell and his Christian fundamentalists, support for the Jewish state is founded on the literal interpretation of Abraham's biblical covenant granting the land of Canaan to Abraham and his "seed."

Falwell also is using his friendship with Begin to counter the widespread belief that the Moral Majority membership is rife with anti-Semitism.

That view has been fostered by public statements such as that of the Rev. Bailey Smith, president of the Southern Baptist Convention, who said that "God Almighty does not hear the prayer of a Jew" and Falwell's own remark at an "I Love America" rally a year ago that a Jew "can make more money accidentally than you can on purpose."

Falwell says he was only making a joke, and goes out of his way to declare undying support not only for Israel but for "Jewish people everywhere."

Asked if events such as yesterday's meeting serve to counter concerns that anti-Semitism is rampant within right-wing Christianity in general and the Moral Majority in particular, Falwell said:

"I think it does. I think it helps both of us to stand side by side."

Falwell brought 18 guests to the meeting with Begin. Most were evangelical Christian ministers, but Falwell included his homestate Virginia governor, John N. Dalton, and the state's U.S. senators, John W. Warner (R) and Harry F. Byrd Jr. (I).

Neither the prime minister nor his spokesmen elaborated on whom Begin had in mind when he said people are trying to separate him and Falwell.

Falwell said: "There are those persons in Israel and in the Jewish community of the United States who would disagree with us on social issues . . . like abortion and who do not like the relationship the prime minister has with us."

Falwell said his fundamentalist reading of the Bible shows its applicability to current geopolitical crises.

"I believe history supports the premise that God deals with nations as they deal with Israel," Falwell said. He added that the Bible explicitly warns against "rulers and potentates who dare touch the apple of God's eye . . . . If we could get Adolf Hitler out of hell for 30 seconds, he'd say 'Amen!' to that."

He continued:

"The Soviet Union makes a terrible mistake in their harassment of and persecution of Jews . . . a fatal mistake."

Falwell's aides worked frantically at the last minute to gather guests and publicize the meeting.

As Calvin Thomas, the Moral Majority's vice president of communications, observed:

"When you're taking over the world, it gets a little hectic at times."