Forty years before he took Turkey by storm leading a party with Islamic roots to power in an avowedly secular republic, Recep Tayyip Erdogan was a soccer player of no small promise. He brought to the game explosive speed, impressive stamina and a particular talent for keeping one eye on the ball and the other peeled for his old man.

Soccer was considered vaguely scandalous in the poor, devout neighborhood where Erdogan's family had migrated from the conservative countryside. Some saw in the game echoes of the brutal slaughter of the prophet Muhammad's grandchildren, whose killers made sport of kicking their severed heads.

"It was a wrong Islamic interpretation, but old people believed it," said Saban Sari, who played opposite Erdogan. "Times change. Today I'm playing football with the imams of the mosque."

In Turkey -- not to mention the Western world that long has considered it the best model of a democratic Muslim nation -- the question is whether Erdogan has changed as well.

As the charismatic chairman of the triumphant Justice and Development Party, Erdogan, 48, emerged from the Nov. 3 parliamentary election as the most powerful man in Turkish politics. But he is also the most problematic. The office a winning party chairman would be expected to assume, prime minister, is closed to Erdogan -- along with every other public post -- by his 1998 conviction for "Islamic sedition."

The party's 50-member governing board is scheduled to meet this week to decide on a name to forward to President Ahmet Necdet Sezer, who formally appoints the prime minister. In a Muslim nation founded on strict secular rules, Erdogan entered public life under the banner of political Islam. The movement is based on a literal interpretation of the Koran's many instructions on governance, demanding that Islamic law, or sharia, become the law of the land. And Erdogan, while a leader of the now-defunct Welfare Party that governed Turkey for 12 erratic months ending in 1997, sounded like a true believer.

"Thank God, I am for sharia," Erdogan once said. And: "One cannot be a secularist and a Muslim at the same time." And: "For us, democracy is a means to an end." Such statements haunted the former Istanbul mayor through this year's election campaign, which ended Nov. 3.

This time, Erdogan's new party, Justice and Development, disavowed political Islam and swept into power talking not religion but economics. In assembling the first single-party majority to rule Turkey in more than 10 years, AKP, as Justice and Development is known in Turkey, marshaled popular outrage at an insular political establishment blamed for the country's worst recession in half a century.

That mattered little to Turkey's secular establishment, however, and skepticism over AKP's professed commitment to secularism remains so widespread that it's the context for jokes among the party faithful. At the AKP Istanbul office last week, a district chairman left visiting reporters with a wry smile and a word of warning to the colleague remaining behind:

"Don't tell them about the hidden agenda!"

Some say the easy humor reflects a new reality.

"I know that they gave up Islamism. They are ex-Islamists, that is my personal feeling," said Rusen Cakir, an AKP critic and author of "Erdogan: The Story of a Transformation." "They became another thing. But what, I don't know."

The question has significance beyond Turkey, a country of 67 million that for centuries has been a natural bridge between East and West, Islam and Christendom. But in Turkey, a strategic U.S. ally valued for its stability -- especially in advance of a possible war in neighboring Iraq -- the rise of Erdogan's party highlights the peculiar brand of democracy that has taken root in a political system where mere expressions of faith have been forbidden.

"The first time I went to America I was struck by the way politicians were talking," said Ali Carkoglu, a political scientist in Istanbul and defender of Turkey's strict secularism. "They were constantly making reference to God!"

For half of the last millennium, Istanbul was the political seat of Islam. The sultans who ruled an Ottoman Empire reaching from the Balkans through the Holy Land also maintained the caliphate, or head of the world Muslim community.

The gradual decline of the empire tracked the rise of Europe, a situation not lost on many educated Turks, who lamented a reluctance to embrace obvious advances, such as the printing press, on the grounds that they originated with "infidels."

When the Ottomans finally collapsed after World War I, an army commander who came to be known as Mustafa Kemal Ataturk founded the nation-state of Turkey. Passionate in his belief that progress lay in emulating the West, Ataturk set about subduing Islam as a political force, bundling the caliph onto the Orient Express and enforcing secularism as the foundation of the republic.

In the eight decades since, secularism itself has come to resemble a state religion in Turkey. Personal expressions of faith that are protected as fundamental rights in the United States and Europe -- such as a woman covering her hair, as the Koran advises -- are grounds for denying admission to state universities or employment as a civil servant.

For men, beards arouse the same opprobrium, as Erdogan discovered in 1980 while captain of the municipal transit company's soccer team.

"Erdogan had a little beard, and that brought pressure on him," said former teammate Dursun Kaya, tears welling at the memory. The Turkish military, which regards itself as guardian of Ataturk's vision, had taken power from a civilian government, and a lieutenant pressured Erdogan to shave.

"He was a natural leader," Kaya said of his friend, who lost his passion for football along with his whiskers. "However, his political side was always there."

The son of a civil servant and a housewife, Erdogan reflected the Kasimpasa neighborhood of his youth, a rough collection of wooden shanties, outdoor plumbing and water drawn from wells. "He was a bit of a hard guy," said an associate. But he was always religious, and grew more so after his father sent him to a state-run religious school.

His teammates called him "Imam Beckenbauer" because he was talented, like German superstar Franz Beckenbauer, and because he declined to join them at the Hilton bar. But he pressured his mates to pray only once, before a game in a more devout neighborhood, Kaya said.

In the mid-'80s, Erdogan joined the Welfare Party, an organization that rose from Turkey's Nakshibandi movement, a sect in the moderate Sufi order of Islam's Sunni branch. The party, like the sect, advocated neither replacing Turkey's secular republic with an Islamic state nor its Swiss-based legal system with sharia. The emphasis was on religion's usefulness in lifting personal morality to improve public life.

Turkish voters put Welfare in power in 1996, and the party's leader, Necmettin Erbakan, became prime minister. But Erbakan unsettled Turks by inviting religious leaders to his official residence and visiting Libyan leader Moammar Gaddafi, who insulted him. The "nightmare" of Erbakan's government, as one Turkish newspaper headline put it this week, ended in 1997 in a widely applauded "soft coup" engineered by the National Security Council, the military-dominated body that oversees elected governments.

Erdogan, meanwhile, spent four years as mayor of Istanbul, a tenure that was widely regarded as impressive. The ancient city, split between Asia and Europe by the splendid Bosporus Strait, had swollen to 10 million by economic migrants like his parents. Between 1994 and 1998, Erdogan's administration installed water lines, sanitation and transit systems.

"He cared about poor people," said Fikri Sagkol, a retired policeman, pointing to the apartment blocks that replaced the hovels of Kasimpasa. "It was rough in our day."

But Erdogan's provocative comments on sharia and democracy, as well as moves restricting the availability of alcohol in Istanbul, rankled the military. At a defiant 1998 rally, he read a poem describing mosques as barracks and minarets as helmets. He was convicted of Islamic sedition and sentenced to 10 months in prison, though he was released after four. His punishment remains controversial, not least because the offending poem is recommended reading by Turkey's Ministry of Education.

Some associates say that, during the Welfare days, Erdogan merely reflected his environment.

"At that time, the party he was serving in, they were always spelling out religious things, so he used to say the same things," said Mehmet Muezzinoglu, the AKP Istanbul chairman.

"He was always more or less moderate," said Sari, who after facing Erdogan in soccer squared off in politics, running against his old friend in a local election before joining AKP last year. "But when he made politics in [Welfare], there was a change in his language."

Others are less generous.

"Tayyip Erdogan was a little copy of Erbakan," said Cakir, the biographer. He recalled Erdogan providing militant, "reflexive Islamic" replies to questions apparently unrelated to religion.

"He was really Islamist," Cakir said. "Maybe not like the Muslim Brotherhood in Egypt or like Hezbollah, but in the context of Turkey he was really an Islamist."

After Welfare was banned in 1998, its leadership dividing into rival camps. Erbakan led conservatives into a new party, called Contentment. It finished eighth Sunday, with 2 percent of the vote.

Moderates founded AKP, which won the election with 34 percent -- almost double the second-place finisher's total and, under Turkey's system of proportional representation, enough for a parliamentary majority.

AKP's founders, including Erdogan, described the party as "conservative democratic" and likened it to the Christian Democrats of Europe, who ground their policies in the dominant faith of their constituents but take care not to lay religion over politics.

"AKP is not a religious party," said Muezzinoglu, the Istanbul chairman. "But it's a party in which religious people can feel at home, can feel at peace."

The party looks secular. Unveiling the AKP platform Sept. 29, Erdogan was introduced by a woman in a sharp Western suit and flowing hair. The platform he read out hit hard on economic issues and government management and scarcely touched on religion. But two out of three women chanting in the audience wore head scarves, as does Erdogan's wife.

Party officials and others say the Western appearance reflects not only political necessity but also a realization that its future lies where Ataturk pointed: in Europe. Inside the European Union, which polls show 80 percent of Turks want to join, Muslims have the right to wear head scarves and beards anywhere. They also live substantially better, a goal to which Erdogan gave full throat at AKP's huge rallies.

"Our first priority is the European Union," Erdogan said in an election-night interview of an organization he years earlier dismissed as a "Christian club."

"We are truthful," he said. "We are decent. We are honest. We are very sensitive to basic rights and freedoms."

Three days later, in a symbolic gesture that made headlines, AKP kept its cafeteria open through the start of Ramadan, the month when Muslims forgo food and drink during daylight hours.

"The religious issues are not the issues people expect Mr. Tayyip to do anything about," said Sagkol, the retired policeman, gesturing to the new streets and homes of Kasimpasa. "I don't think sharia can ever come to Turkey. If it ever did, then Turkey would be finished. We'd be just like Iran!"

Recep Tayyip Erdogan, leader of the Justice and Development Party, which won recent elections, salutes supporters as he leaves a mosque in Ankara.