The archbishop said Christian-Muslim relationships had progressed
The Archbishop of Canterbury has released a message for the Muslim festival Eid.
Sending "warm good wishes" to the Muslim community, Dr Rowan Williams cites recent positive examples of Christian and Muslim "engagement".
However, he mentions racist incidents, terrorism cases and persecution of Christians abroad as "darker episodes".
"My great hope for the coming year is that our festivals will increasingly be occasions of mutual gladness," he says.
Dr Williams continues: "This will happen the more we come together to address the issues of our times and the more we stand out against the darker currents present in our society.
"In this spirit may this festival be a joy to you and a gladness to others."
In the message for Eid, the festival which marks the end of Ramadan, Dr Williams points to improvements in relations between the Christian and Muslim communities.
"Much has been achieved in the building of relationships between Christians and Muslims in local neighbourhoods, in the workplace and in the very many dialogue and discussion forums that have grown up in recent years," he writes.
He refers to the "many occasions in the past year" when has joined Muslim colleagues for discussions on "subjects of common concern".
The Archbishop writes: "I think particularly of the discussions leading to the preparation of the new White Paper on international development... the religious leaders' statement on the occasion of the G20 London Summit and the seminar on faith and finance arranged by the Christian Muslim Forum."
However, he continues: "There are nevertheless all too many darker episodes to set against these signs of hope and light".
He points to "the provocative actions of small racist groups in recent months in Luton, Birmingham and Harrow".
Other examples include: "The conviction of young men of Islamic conviction for attempted mass murder in the air; the violence against Gaza and southern Israel; the killings of Christians in Pakistan and Nigeria; and the continuing detention of the Baha'i leadership in Iran."