GAZA CITY, Occupied Gaza Strip (AP) _ ''In the Name of Allah, come help your Moslem brothers,'' blared a voice from a minaret as Palestinian teen-agers battled Israeli soldiers.

Islamic slogans and verses from the Koran, or Moslem holy book, were heard here and in other Gazan towns as Arab protesters charged toward Israeli troops hurling stones and bottles.

A sharp rise of Islamic fervor has fueled clashes this month in the overcrowded seaside strip that Israel captured from Egypt in 1967.

Most frightening for the Israeli side is that the mushrooming fundamentalism makes young Arabs fearless in the face of Israeli gunfire.

''We Moslems believe our time for death is preordained,'' Gazan leader Issam al Shawaa said in an interview in Gaza City. ''That is why the Israelis cannot kill us. Only Allah can.''

Reasons for the upsurge in religious zeal in the Gaza Strip are many. Key among them is its striking poverty.

Two-thirds of the Gaza Strip's 650,000 Palestinians live in eight refugee camps, where open sewage runs through narrow dirt streets and more than a dozen people often live in two-room houses of cement blocks and corrugated tin.

Teen-age Palestinians often see little way out of the alleys of Gaza. Their older brothers who made money in the Persian Gulf oil boom are returning now, having lost their jobs in the subsequent depression.

Many who go to school attend the Islamic University in Gaza City, the largest in the occupied territories and one of the principal forces behind the growing fundamentalism.

The school requires its student body of 6,000 to adhere to Moslem laws concerning dress and behavior. Even women who go swimming in the Mediterranean on a hot summer day do so in long dresses and headscarves.

The school also uses the Islamic calendar and writes ''In the Name of Allah'' atop its occasional press releases.

Another factor feeding the fundamentalism is that many Gazans feel isolated and forgotten on their narrow strip of land.

The traditional leaders of the Palestine Liberation Organization have less influence here than in the occupied West Bank, where most of the Palestinian Christians live. As a result, Moslem religious leaders, some influenced by trends in Egypt, are more likely to be a source of solace and support in Gaza.

''When Gazans go somewhere to escape their problems, that somewhere is likely to be the mosque,'' said one United Nations official who has lived three years in the strip and spoke on condition of anonymity.

Rallying cries during demonstrations often come from the mosques. During a clash Wednesday night in Rafah, a city along the Egyptian border, the minaret of one nearby mosque blared to the protesters: ''Don't back off,'' and called on other Palestinians to rush to the area.

One of the key imams, or Moslem religious leaders, in Gaza is Sheik Ahmed Yassin, a powerful, militant preacher and spiritual leader for thousands.

Yassin, who has been paralyzed from the neck down since childhood, often passionately extols his followers to attack Israelis, according to Palestinians who have attended his Friday services.

Yassin was convicted by an Israeli military court several years ago for his activism, but was not jailed because of ill health.

Some analysts say that Israel has failed to fully recognize the dangerous power of the growing fundamentalism.

Moslem fundamentalism ''possesses an inexorable momentum,'' said Yehoshua Palmon, a former adviser to the prime minister on Arab affairs. ''And the government is doing nothing about it, doesn't even seem to be aware.''

Speaking in an interview with the Jerusalem Post, Palmon suggested the Israeli government start fighting the problem by giving more leeway to traditional Moslem institutions, such as religious courts, to try to strengthen democratic tendencies.