He was dressed in the trademark black of the Mahdi army, the militia led by the Shia Muslim cleric Moqtada Sadr.
But 18-year-old Mohammed Odeh looked perfectly at home attending prayers outside the main Sunni Muslim mosque in Baghdad.
"I came to strengthen our religion and prove to the Americans we are one people," he said.
The US has faced an uprising from Moqtada Sadr's Mahdi Army
Sunnis and Shias in Iraq have increasingly begun to act like one people since members of both communities took up arms against occupation forces this month.
In central Iraq Sunni guerrillas fought an American force that launched an offensive against the city of Falluja, retribution for the brutal murder of four US security contractors there.
In Baghdad and southern Iraq, Moqtada Sadr's Mahdi Army took over police stations and battled occupation troops in a widespread rebellion that took the coalition by surprise.
The fighting on two fronts raised the spectre of America's worst nightmare: a Shia revolt joining forces with the Sunni dominated insurgency in a national uprising against the occupation.
Even before the current crisis Moqtada Sadr had reached out to Sunni clerical movements like the Muslim Scholars Union, joining forces in demonstrations against sectarian killings and Iraq's recently approved interim constitution.
With the current fighting that political alliance has led to wider expressions of solidarity.
Shias have been donating food to Sunni mosques organising aid convoys for Falluja.
Graffiti in Baghdad proclaims a common cause, declaring "Long live the people of Falluja and Sadr City", the Shia slum where US troops took on Sadr militias.
Sunni Muslims are also fighting US forces
There are expressions of mutual support. Graffiti in the Sunni town of Ramadi praises Moqtada Sadr for heroic deeds, while the young cleric has declared support for Falluja, and called for united efforts to end the occupation.
There've even been some reports of minor military co-operation, with Sunni and Shia guerrillas travelling to each others fronts.
But there are differences between the two revolts.
Falluja is a longstanding confrontation which has been simmering since the start of the occupation. It's the heartland of Sunni resistance, a potent mix of nationalism, tribalism and conservative Islam that even Saddam Hussein found difficult to tame.
The Shia rebellion was the result of a US crackdown on the Sadr movement.
It was fuelled by rising Shia discontent, not so much with the occupation as with its policies - particularly what many Shias saw as American foot-dragging on elections for an Iraqi government.
The two conflicts have separate negotiating tracks and separate solutions.
And they have different goals, as far as it's possible to determine.
It appears that the aim of the Muslim Scholars Union and the Sunni resistance is to force an American withdrawal or at least get the occupation to recognise them as authentic Sunni representatives.
The aim of Moqtada Sadr seems to be mostly about increasing his weight in the Shia religious establishment by becoming the dominant political voice within it.
Not so much a national resistance than, as perhaps the seeds of a new national identity, built on what's common to both.
For now only one thing is clear, says Iraqi analyst Wamid Nathmi. Whether through stupidity or ill thought out design, the Americans have provoked a reality their entire project in Iraq was designed to suppress: a revolt that expresses Iraqis' common Arab and Muslim identity.