By Elizabeth Blunt
BBC News, Addis Ababa
Ethiopia's former Derg junta disapproved of religion
This week Addis Ababa is playing host to a gathering of church leaders from all over the world.
Ethiopia - which follows its own ancient Coptic calendar - has just celebrated the start of the new millennium.
And the head of the Ethiopian Church has invited his colleagues to take part in a conference on the problems of the world today, and to join him in celebrating Meskel, the first big festival of the Ethiopian religious year.
For the church, Meskel commemorates the finding of the true cross - Meskel in Amharic - by St Helena in the fourth century AD.
St Helena was the mother of the Emperor Constantine and she went to Jerusalem to look for the cross on which Christ was crucified.
There, the story goes, she was advised to light a fire which would show her where to look.
The smoke from the fire pointed to the place where the cross was buried.
Meskel celebrations are colourful
St Helena then gave pieces of the cross to all the churches.
The Ethiopian Church still claims to have its own piece, hidden away at the remote monastery of Gishan Mariam, and celebrates the finding of the cross every year.
But the religious event has clearly got mixed up with older, traditional celebrations.
People are also celebrating the new year, the end of the long, dark rainy season and the return of sunshine and light.
The fields are full of flowers - especially the bright yellow Meskel daisies - and the crops are starting to grow.
Meskel is always a colourful occasion, an excuse for bonfires and parties.
Children make the most of it, knowing that it will be the last festival before they have to go back to school for the new academic year.
Issues for discussion include terrorism, Aids and social change
The biggest public celebration (and the biggest bonfire) is always in the huge open space in the centre of the capital, Meskel Square.
The Derg, the former communist military dictatorship, disapproved both of religion, and of its citizens having fun, and renamed it Revolution Square, but it has now got its old name back.
The patriarch of the Ethiopian Church always attends, and this year he is joined by other religious figures.
The Oriental Orthodox churches - Egypt, Ethiopia, Syria, Armenia and South India - are the inheritors of a very ancient Christian tradition and have stood out against various attempts at change over the centuries.
But although they are sister churches, they have been quite isolated from each other.
Their patriarchs have only once all met together - in Addis Ababa in the time of Emperor Haile Selassie.
All the Oriental churches have sent senior church leaders to Addis Ababa this week.
Alongside them is the ecumenical patriarch of Constantinople, and many other senior figures from the eastern group of Orthodox churches - like those in Russia, Serbia and Greece.
And the Ethiopian patriarch, who is currently one of the presidents of the World Council of Churches, has invited the WCC churches as well.
But an invitation was not extended to church leaders in neighbouring Eritrea, with whom Ethiopia has a troubled relationship.
The Ethiopian patriarch said he very much wished he could have invited them but it was just not possible.
As well as enjoying the Meskel celebrations, the church leaders attended a conference to discuss some of the big issues currently facing the world and their church members.
The problems of conflict and terrorism were on the agenda, as well as Aids, climate change, poverty and the need for social justice.