While thousands of Turks edged through this city's trendiest districts, glimpsing the devastation left by four deadly bombings last week, thousands of others streamed into mosques in humbler quarters - where the view of the attacks looks markedly different.
"It can't be Al Qaeda because they wouldn't launch an attack that would hurt Muslims," says Suleyman Gencturk, a young man who blames the bombings on Israel and the US. Mr. Gencturk sells religious CDs in Fatih, a working-class neighborhood which has a more devout character than the upscale areas where suicide bombers killed 57 and wounded hundreds more. Here, men in skullcaps and women wearing headscarves - officially discouraged by Turkey's secular state - are far more prevalent than in the shell-shocked neighborhoods of Beyoglu, Levent, and Sisli, where the pace is more European than Middle Eastern.
The chasm between those two worlds was lit up by the bomb- ing campaign, which Turkish investigators say bears Al Qaeda's logo. But, more likely and more troublesome, homegrown Turkish fundamentalist groups could be responsible for planning the attacks - with little more than ideological inspiration coming from Osama bin Laden's group.
Experts on Islamic groups in Turkey say they are fueled not only by international grievances but by the Turkish state's stridently secular and pro-Western outlook. Such groups are trying to destabilize the ruling AK Party, an organization with Muslim roots that has not delivered on promises to make Turkey more Islamic.
"The main target was to shake the AK Party, to shake the Turkish Army and demolish their cooperation and their balance of power in Turkey," says Faik Bulut, who has written several books on Islamic fundamentalist groups in Turkey. The most that Al Qaeda has offered to the equation, he estimates, is inspiration. "There is a kind of ideological relationship with Al Qaeda, with the big cause - which is jihad and anti-Americanism."
If the goal were to send the government reeling, mission accomplished.
The AK Party's roots reach back to the Welfare Party in the 1990s, which tried to shift Turkey's orientation away from the West and towards Muslim neighbors like Iran and nearby Arab countries.
While AK has taken a far more cautious, low-key approach, it has not been terribly keen on most everything Washington has asked of it since its election one year ago.
The government - and the overwhelming majority of Turks - opposed the war in Iraq. While Turkish leaders did eventually throw tepid support behind allowing US troops to cross through here, a measure which failed in parliament, they never made the case for the Iraq war to the public. Now, especially after Prime Minister Recep Tayyip Erdogan spearheaded a vote last month to send Turkish troops to Iraq, the government is left with an image - at least to its most conservative constituents - of being co-opted by US interests and dragging Turkey into the line of fire.
On the domestic front, the party has also failed to make headway on hot-button issues for religious people - like a ban that prevents women with head scarves from entering most government buildings.
"Everybody said the war against Iraq would open a Pandora's box. People are saying, 'If there wasn't this war, we wouldn't be targeted,'" says Fehmi Koru, a columnist for Yeni Safak, a newspaper with a conservative religious readership. "There was no such thing as [mass suicide bombings] happening in Turkey before the Iraq war. We have not been a part of the Iraqi quagmire, but now Iraq is in Turkey - and terror is inside our territory."
Over the weekend, several thousand protesters here and in other Turkish cities condemned the bombings - and similarly laid blame at the doorstep of US policy in the Middle East.
Now, say experts, the Turkish government must weigh whether to strengthen its ties and cooperation with the US, Britain, and other allies in the terror war, or try to distance itself from alliances that make Turkey likely to be a more frequent target.
"I think Turkey has two choices," says Mr. Bulut. "To choose a policy closer to the US and Israel, which will make Turkey an attraction for more terror attacks. Or to chose to cooperate with local countries that want stability in the region - who can help build a security belt around Turkey's border."
Mr. Erdogan has so far shown himself able to straddle the difficult East-West divide, condemning the attacks while appealing to religious sensibilities. The occurrence of the bombings near the end of Ramadan, the Islamic holy month, he said, should increase any true Muslim's sense of outrage.
"Those who shed blood and killed innocents in these holy days will have to account for themselves in both worlds and will be doomed till eternity," Erdogan said.
This is, after all, a time in the Islamic calendar for self-reflection and soul-searching. On Friday, worshippers at the Fatih mosque were preparing for Kadir, a special night in Ramadan where all prayers for forgiveness are said to be answered. The imam, a wispy 30-year-old who had memorized the Koran by the age 12, says the Islamic holy book deems human life precious.
"There is no place in any holy book for such actions," says Esat Shahin, who wears a neat blue suit and trim black beard. While he offered prayers for the victims and wished healing for the injured at the weekly prayer service, attending by some 7,000 worshipers, he didn't address the bombers' deeds directly. Friday sermons in Turkey are closely monitored, and preachers know to leave out political content.
The danger that at least some young Muslim men - however marginal - are getting swept up by Al Qaeda's ideology is, the imam says, not for him to worry about. "We want to touch people's hearts and souls - not their mentalities."