Atheists aim to ban Jesus and declare war on Christmas
The school choirs had been practising for weeks, excited about leading the carols at the Christmas festival at a local Catholic shrine.
Then the letter from atheist campaigners arrived and the children learnt they would not be allowed to sing at the Grotto but would have to find a "non-religious" venue instead.
The 25-year tradition in Portland, Oregon, is one of thousands of targets of a group that has declared "war on Christmas".
"There are a lot of Americans who think Christianity owns this month," said Dan Barker, a member of the Freedom From Religion Foundation (FFRF). "We have complaints from all over the country at this time of year."
The FFRF's 23,000 members have mobilised to ban Jesus from classroom plays, silence school choirs and take down nativity scenes.
At this time of year, Mr Barker said, his office becomes a war room: "It really ramps up. Our legal staff get ready, writing template letters for each state and district, ready to deploy them at any moment."
The campaigners seek to enforce an absolutist interpretation of the US constitution's separation between church and state, prompted in part by its belief that the religious Right is attempting to undermine secular state schools and the rights of non-believers. Its members write to state schools and government institutions, threatening legal action if Christianity is cited in their winter celebrations.
If the letters fail, the FFRF sometimes make good on its threats, said Mr Barker, reciting a long list of cases it is fighting in the courts.
He spent much of his life as a preacher before gradually realising "that what I was preaching was not true". He says the group is not trying to "kill" Christmas, and that many members still celebrate the holiday.
"We still have a tree; we just don't put an angel on the top," he said. "We believe Christians stole the holiday from the pagans. It is the winter solstice."
If a Christian display is in a public space, rather than on the property of a government-affiliated body, freedom of expression protects it. All that the atheists can do then is file petitions to put up their own hoardings.
This has given rise to scenes of Jesus in the manger, surrounded by posters denying the existence of God.
"In Franklin County [Indiana], this year they had a nativity display outside the courthouse," said Mr Barker. "We put up our signs and then other groups did too. Even the Satanists got involved. The courthouse looked like a mad house."
Displays are becoming ever more inventive. In his home town of Madison, Wisconsin, Mr Barker has a nativity scene, "but instead of Jesus, we have the Bill of Rights in a manger".
One Ohio man provoked worldwide attention, and was fined for a planning violation, last year when he erected a "zombie nativity" outside his home.
This year, the display is back: Joseph is depicted as a gaunt, grey figure with hollow black eyes and blood dripping from his mouth. Mary has scars all over her face and stitches on her lips. And the baby Jesus is a small, bald-headed monster with sharp teeth and glowing yellow eyes.
The war is also fought with billboards. Last year a group called American Atheists brought its billboards to the southern Bible Belt states.
Giant advertisements in Tennessee and Arkansas showed a young girl writing her letter to Father Christmas. "Dear Santa, All I want for Christmas is to skip church! I'm too old for fairy tales," she wrote.
This year, Father Christmas replied. "Go ahead and skip church!" Santa urges on a billboard in North Carolina. "Just be good for goodness' sakes. Happy Holidays!" (© Daily Telegraph, London)