For 45 years, Father Ibrahim Ayad has begun each day celebrating mass. These days his frail, stooped figure can be seen at daybreak slowly walking through the war-pocked streets of West Beirut to the Dominican Sisters' convent, his fraying black cassock and padre's hat conspicuous in the Moslem-dominated sector of the divided capital.

It is hardly the image of a man who, upon finishing mass, starts work as an official of the Palestine Liberation Organization. Nor is it the picture of a man recognized throughout the world as the president of the Latin Ecclesiastical Court of Lebanon -- and for his important connections at the Vatican.

Father Ayad is a Palestinian priest, born 68 years ago in Bethlehem, who startles outsiders by mentioning PLO chieftain Yasir Arafat and Pope John Paul II in the same sentence -- and with the same admiration.

But the connection is not as incongruous as it might seem, for Ayad represents one of many factions trying to bring together the Roman Catholic Church and Arab guerillas whose goal is a return to their former homeland -- today's Israel. And his move has received quiet encouragement from men in the baroque buildings of the Holy See and the shabby PLO headquarters in the Lebanese capital.

It is a relationship that budded under Pope Paul and accelerated under the more political and aggressive John Paul II. Its foundation is a crucial and often overlooked fact: one-quarter of the Palestinians are Christian and, according to Arafat, even more -- 35 percent -- of the PLO is Christian. There are Christians, including many Catholics, in leadership positions in all eight factions of the PLO.

Should there be another Palestine, this nascent friendship could grow into the Vatican's closest in the region, with the Palestinians potentially providing an important link between Christians and Moslems in the Middle East.

Within one year of John Paul's election, the infrequent contacts had become a discreet dialogue and are now at the stage that both sides are considering a "substantial meeting," according to both Vatican and Palestinian sources. That means Arafat and John Paul, a possibility being pursued "with intensity" by the PLO and with "high interest" by the pope's office, according to these sources.

John Paul has clearly made the Palestinian problem a priority of his papacy, personally directing a shift in policy, according to a member of the Vatican secretariat of state, despite opposition from conservative members of the Curia, or Vatican cabinet.

The first direct contact, according to a number of sources in the Vatican Secretariat of State, was a series of letters in 1979 between John Paul and the Palestinian leader. Later that year, during the pontiff's trip to Turkey, he met with PLO representative Abu Faras.

The contacts became public in 1980, when Arafat's aide Afif Sufieh, a Catholic, had an audience with the pope. Sufieh delivered a letter from his Moslem boss to the leader of the Catholic world, a letter in which Arafat quoted the Bible extensively and invited the pope to lead the first procession of Palestinians back to their homeland if and when a settlement is reached.

In a flowery but concise handwritten script, Arafat outlined his position on Middle East issues. He also wrote: "Please permit me to have a dream that I am seeing you going to Palestine and Jerusalem, surrounded by returning Palestinian refugees, carrying olive branches and spreading them at your feet," evoking images of another pilgrimage two millenia ago. The five-page letter was signed: "Commander-in-Chief of the Palestinian Revolution."

The two now exchange holiday greetings: Arafat sends the pope a Christmas card, while the pontiff includes the PLO chairman in his annual cabled greetings to Islamic leaders.

One of the five accredited Jewish "observers" at the Vatican -- all from non-Israeli groups -- marked Oct. 5, 1980, as the turning point when, in a speech in the southern Italian village of Otranto, John Paul publicly criticized Israel for the "conspicuous exclusion of many Palestinians from their homeland," a virtual endorsement of Palestinian rights.

What really set Israeli alarm bells ringing however, was what not too long ago would have been considered a most improbable meeting: the right-hand men of both Arafat and the pope, t.ete-Ma-t.ete, as Cardinal Agostino Casaroli and Farouk Kaddoumi were last March.

Church insiders labeled the meeting "highly successful and meaningful." Kaddoumi went further, telling reporters the Vatican expressed "solidarity" with Palestinians fighting for their homeland. The Israeli foreign ministry immediately registered its "amazement and regret" at the news of the talks.

Jewish representatives at the Holy See had, up to this point, not been worried by the budding relationship. Indeed, they had felt confidence in this pontiff, who was forced to go underground during the Nazi occupation of Poland while Germans hunted him for alleged assistance in hiding and delivering supplies to Jews and others.

Those "credentials" marked a major change in papal performance, in Israeli eyes, after a long history of hostility, most recently marked by Pope Pius XII's alleged lack of help to Italian Jews during World War II, and the discordant meeting between Pope Paul and Golda Meir in 1973. The Vatican still does not recognize Israel, technically because of its "uncertain" boundaries.

But Kaddoumi's visit and the Otranto speech triggered old anxieties again. A congress of the world's main Jewish groups last April declared: "The Vatican-PLO meeting cannot in any way be reconciled with John Paul's repeated forthright condemnation of terrorism and violence."

At the same time, the activist pontiff was also moving quickly to end the ancient animosity between Christians and Moslems, another source of annoyance to the Israelis.

Last February, during a brief stopover in Pakistan, John Paul visibly stunned President Zia ul Haq by calling for "closer collaboration and cooperation" between the Catholic and Islamic worlds in solving problems of mutual concern, meaning the Middle East.

Back in Rome, the list of Arab leaders dropping in to pay their respects kept growing: King Hussein, Saudi Arabian Foreign Minister Saud Faisal, cabinet officials or ambassadors from Iraq, Egypt and the Islamic conference. Other dialogues were going through emissaries.

Also worrying the Israelis was the presence in Rome of former Archbishop of Jerusalem Hilarion Capucci, the Christian Arab prelate who was convicted by the Israelis of gunrunning for the Palestinians. He was released from prison only after Vatican intervention and a pledge that he would be physically and in professional terms cut off from the Middle East.

The Israelis blasted Capucci for setting up the Kaddoumi meeting, thereby breaking the terms of his release. The Vatican and Capucci both denied his involvement. Indeed Ayad, half the size but twice as powerful as Capucci, had far more to do with the meeting.

But at the center was the pope, who wanted the contact, according to an American scholar at the Vatican. "He believes the Palestinians must be included in the peace process, if there is to be a meaningful solution," the U.S. priest said. "I think he would rather see one country, where all have equal rights. But John Paul is not willing to go further, publicly, than the European community.

"There were two side issues that forced him to speak out, to take a stand. One was the Israelis' position on Jerusalem. He is violently opposed to their decision on Jerusalem (making it their "united and eternal capital"), because he believes it should be a neutral shrine for Jews, Christians and Moslems.

"The Vatican is also concerned about the implications of the exodus of Christians from the Middle East -- from Israel, Lebanon and Egypt particularly. In a way, we need the Palestinians. They are among the few Christians who are staying."

But perhaps equally interesting is the fact that all this activity is occuring at a time when the church has repeatedly called on priests and nuns to sever other political connections. These other political connections range from young Jesuits aiding banned unionists in Brazil, to the more radical clergy assisting guerrillas in the Philippines to, in the United States, the celebrated case of Father Robert Drinan, who was forced to step down as a Democratic representative from Massachusetts.

But this is not the case for Father Ayad, who says "No, even some (church officials) have encouraged me," a fact confirmed by a high-level U.S. priest at the Holy See. "Ayad is an important link because he is respected by both sides. He is not a wild man like Capucci," the priest explained.

Yet it is no secret that Ayad undertakes extensive missions on behalf of Arafat to Latin America, Europe and the United States. "All peaceful," he smiles coyly, before being asked.

Arafat even wanted to nominate him for the highest, 15-man Palestinian Executive Committee at the PLO summit in Damascus last April, but Ayad backed off, claiming he already had too much to do.

Ayad certainly sees no conflict in his two full-time jobs, one a mission of brotherly love, the other promoting struggle: "When you work for a just cause you comply with Christian principle, which commands, orders you to fight."

He often quotes the Book of Sirach (Ecclesiasticus) from the Catholic Bible, in support of his PLO activity:

"Deliver the oppressed from the hand of the oppressor; let not justice be repugnant to you." (4:9)

And: "Even to the death fight for truth, and the Lord your God will battle for you." (4:28)