BOB ABERNETHY, anchor: We have a special report today on Islamic fundamentalism in Saudi Arabia. It's called Wahhabism, and its strict interpretation of the Qur'an has led to curbs on human rights and religious and social intolerance that many observers find dangerous, especially if Wahhabis encourage terrorism against non-Muslims.

Kate Seelye of National Public Radio visited Saudi Arabia recently, talked with hard-line clerics and their critics, and sent us this report.

KATE SEELYE: Friday in the seaport of Jeddah, hundreds of worshippers direct their prayers toward Mecca.

College freshman Nawal al Khalawi says Islam is her identity.

NAWAL AL KHALAWI: It's the way I live my life. Since I was young, this is the way I was raised. You know -- at school, with my family -- everything has to do with my religion.

SEELYE: Here in the birthplace of Islam, law is based on the Qur'an and religion governs daily life. Shops are obliged to close three times a day for prayer while followers head to the mosque.

Saudi television devotes hours to programs about religion, frequently broadcasting images of the holy city of Mecca -- site of the hajj pilgrimage, one of the five pillars of Islam.

But since the 9/11 attacks, religion in Saudi Arabia has come under increasing criticism. The kingdom's rigid interpretation of Islam has helped contribute to extremism and terrorism, say U.S. officials. Wahhabism, as they call it, must be reformed.

Prominent cleric Sheikh Abdel Muhsin al-Ubaykan rejects this criticism. He says Saudis are simply following the true path of Islam as preached by the 18th-century religious reformer Mohammed Abdel Wahhab.

Sheikh Abdel Muhsin al-UBAKYAN (Cleric) (Through Translator): He came and found people worshipping idols, graves, and trees. "This is not Islam," Abdel Wahhab came to say, "this is wrong," and returned people to the correct understanding of Islam.

SEELYE: It was here, in this once thriving desert town of Dirayah, that Abdel Wahhab formed an alliance with local tribal leaders, the al Sauds.

From this 18th-century political and religious union, modern Saudi Arabia was born. Today, the followers of Mohammed Abdel Wahhab give the ruling family religious legitimacy. In exchange, the clerical establishment is given nearly free rein to determine Saudi Arabia's social policy.

In malls and other public spaces, religious police guard against un-Islamic behavior and enforce the country's strict social codes. Not only are women forbidden to drive, they are restricted from working in certain professions. The genders are segregated at work as well as in restaurants, banks, and other establishments.

Sheikh al-UBAKYAN (Through Translator): In modern society, there is corruption that results from the mixing of men and women. From desire comes adultery, illegitimate children, and sexual disease.

SEELYE: Islam is the only recognized religion. Non-Muslims are banned from public worship despite the presence of non-Muslim workers here. Many Wahhabi clerics like Suleiman al Duwaish preach intolerance of other faiths, as well as of Muslims who don't share their religious interpretation.

SULEIMAN AL DUWAISH (Cleric and Religious Scholar) (Through Translator): Anyone who is not a Muslim is an infidel no matter what religion he is. We also recognize the difference between which of these infidels deserve to be cursed and those who don't. God himself differentiated between Jews and Christians. While both being infidels, Christians are closer to Muslims than the Jews and less of an enemy than them as well.

SEELYE: In the past it was taboo to criticize the religious establishment. Saudi society is deeply traditional and conservative. Most Saudis have enormous respect for their spiritual leaders. But a series of deadly Al Qaeda terrorist attacks, like the one against this residential compound in Riyadh two and a half years ago, have begun to change local attitudes.

With the kingdom under attack and security tight, more and more Saudis are starting to ask a tough question: Does their interpretation of Islam indeed encourage extremism and violence? Writer and religious reformer Khaled al Ghannami, a former Wahhabi, believes it does. He says the state has inadvertently nurtured an ideology that has turned against it.

KHALED AL GHANNAMI (Writer): Those teachings encouraged people to come up with ideas that this country must be so pure that nobody else who is not Muslim should set foot in this land and that everyone who comes here is, you know -- he can be killed just for being there.