On the banks of the Tigris, away from the filth and destruction in the rest of Baghdad, dozens of Iraqis dressed in white gather every Sunday to bathe in the river's muddy waters in an ancient rite to purify both body and soul.
The curious scene, which looks as if it were taken straight from a biblical epic film, takes place under the bridge that crosses the Tigris in the Al-Qadisiyah quarter as an astonished collection of local citizenry, foreigners and US soldiers look on.
These are the Mandeans, which the Encyclopedia of the Orient calls the world's only surviving Gnostic religion, with no more than 20,000 adherents living in southern Iraq and southwestern Iran.
For them, the cosmos is made up of two forces -- of light and darkness -- that are in conflict, and out of whose warring the world came. Man was created by the force of darkness, but in every man there is a "hidden Adam," the soul, which has its origin in the world of light.
Baptism is central to the worship of the Mandeans, whose origins are unknown, but who consider themselves the latter-day disciples of the Jewish patriarch Abraham and of John the Baptist, the Jewish prophet who preceded Jesus Christ.
The newly born, the elderly in their final years of life, couples about to marry and the faithful seeking forgiveness for their sins must all pass through the ritual of baptism in the Tigris.
Among this particular Sunday's "purified" are Adel and Nahlem, a young couple who have just pronounced before an elderly priest a series of promises in Aramaic, a cousin of Hebrew that was spoken by Jesus.
The priest anoints their heads with oil, dunks their heads several times in the water and has them take several sips, so that their souls might shine as they wed.
Relatives celebrate their spiritual cleansing with shouts and songs that wish them happiness. The young couple, crowned with olive wreaths, move on to the temple, just a few metres (yards) away, where they exchange their wedding vows.
"Ahead of any important moment in our lives, the soul must be clean," explains the master of ceremonies, Haldun Majid, whose long beard, white tunic and rustic sandals give him the impression of an Old Testament prophet.
For the Mandeans, the flowing water of rivers is central to their worship, and they will drink it even if it is contaminated. "We are never sick. Water is the secret of life and of purification," one believer explains.
The Mandeans say that during the decades of Saddam Hussein's regime they were permitted to perform their rituals discreetly, but were the victims of many injustices.
Even today, they cannot carry out their rites as spelled out in their sacred book, the Ginza Rabba, or Great Treasure, an Aramaic text written in 1291 AD.
For one thing, the staring eyes of outsiders makes them uncomfortable.
"Sometimes we prefer to hold our celebrations in a tank of rainwater that we have inside the temple to avoid the stares of people," says priest Kheyr Ala.
Despite their humble appearance, most of the people taking their ritual dips in the Tigris are from upper class families in the capital, who have driven here in luxury cars to the temple, surrounded by olive trees.
The entrance to the temple is marked by two olive branches in the form of a cross, symbolizing those used by John the Baptist to sprinkle holy water on the assembled crowds.
Also, the riverside ceremonies are sometimes interrupted by American soldiers, Ala says, noting that 33 people from his community, "all of them innocent civilians', died during coalition bombing of the capital at the outset of the war in March.
But this Sunday, US army chaplain Anthony Horton participated in the ceremonies, noting that "their rites are original and authentic, an exact reproduction of the baptism performed by John the Baptist."
Yet the faithful insist that their religion has nothing to do with that of US President George W. Bush, a Methodist Christian.
"The methods, the beliefs and the worshippers are different," Jer Ala says.