Among the more than 1,200 people seated in the Regency Ballroom of the Shoreham on Saturday night were Christian Lebanese, Moslem Lebanese, Palestinians, Syrians, Jordanians and a Benedictine monk.

The monk was a guest. The rest were members of the National Association of Arab Americans, which held the filet-mignon dinner to mark the close of its 11th annual convention. And despite the mixed bag of Middle Eastern faiths, the group's many factions claimed a common belief in two things: peace in the Middle East and strength for the Arab cause.

Jordan's King Hussein was scheduled to speak at the dinner, but according to Jordan's Crown Prince Hassan Ibn Talal, whom the king sent in his place, "obligations prevented him from attending. Among them, meeting with Prime Minister Margaret Thatcher."

Hassan read Hussein's text, which addressed the problems in the Middle East, making it clear these were the king's words.

"Arabs have, in general, been labeled as 'war mongers' for too long," read Hassan. "Ironically, Jordan, and I personally, have recently been singled out as 'obstacles to peace.' "

The speech blamed "Israeli intransigence" as the roadblock to peace for the last 15 years.

"Over the central issue of the Palestine question, it is the Israeli premier, Mr. Menachem Begin, and not President Nasser's successors in Egypt, who stands firm on the three nos: No recognition, no negotiations and no peace," said Hassan. "It is the Israeli premier and not I who vehemently opposed and rejected the Reagan peace initiative of September 1982, and even accused his fellow countrymen of treason were they to consider it as the basis for Middle East peace."

U.S. Rep. Nick J. Rahall (D.-W.Va.), speaking with a West Virginia twang, and emcee for the evening, also took a turn at jabbing Israel in his remarks.

"For those of you who may wonder and may question my accent, it's derived not from West Virginia, but because my grandparents hailed from southern Lebanon," he said. "I only hope that the Rahalls that still reside in southern Lebanon will never speak with a Jewish accent." The crowd hooted, cheered and clapped.

Rahall's sentiments of withdrawing Israeli troops from Lebanon and creating a Palestinian entity on the Israeli-occupied West Bank and Gaza, as envisioned in the Reagan plan, were echoed by NAAA president Robert Joseph.

"The Lebanese are not the only ones who want the Palestinians out of their country," Joseph said. "The Palestinians want the Palestinians out of Lebanon! But they have to have someplace to go. And that's Palestine."

Joseph told of a recent trip to Jordan. He got to his hotel room, looked out and saw construction. "I thought of the settlements and of how many times I heard 'Israel wants peace.' That's a cliche' at this point," Joseph said. "They want peace--a piece of Syria, a piece of Jordan, a piece of Lebanon . . ."

Also at issue were Secretary of State George P. Shultz's recent Mideast trip and Hussein's recent negotiations with Palestine Liberation Organization Chairman Yasser Arafat, who would not give Hussein permission to represent the Palestinian view in expanded peace talks with Israel.

"Gradually, the Jordan-PLO dialogue has lost its momentum," Hassan said, reading from the Hussein speech, and warned the United States against initiating "a policy which it cannot implement.

"The recent visit by Secretary of State Shultz to the area is a clear indication that the president intends to persevere in spite of the difficulties encountered so far." He reiterated Hussein's "commitment to peace." But he said the "Israelis must abandon their siege mentality and accept to live in the region as partners, and not overlords or masters."

Most NAAA members agreed with the remarks and were not surprised that Hussein sent Hassan in his absence.

"The crown prince is extremely knowledgeable himself on the situation in Gaza and the West Bank, occupied territories," said Emile Nakhleh, a professor at Mount St. Mary's College in Maryland and member of the NAAA board of directors. "He's a short little fellow, but extremely energetic."

The banquet seemed to serve not only as a forum for Hussein's remarks, but also as a rallying point for Arab Americans. A nine-minute video program promoted the organization's work.

The officers touted accomplishments: "We're becoming an organization that truly wields political power in the U.S.," David Sadd, executive director of the NAAA, said to the group.

And goals: "The battle for peace in the Middle East will be won in Washington," said Joseph. "We must unite and we must act. We shall wage peace as we have never waged it before."