PHOTO: AFP/EAST NEWS Christian Egyptians living in Greece stage a demonstration in central Athens on January 21, 2010 to protest against the killings of Coptic Christians in Egypt's Nagaa Hammadi. Egyptian President Hosni Mubarak said on Thursday that sectarian strife is threatening Egypt's unity, in his strongest comments yet on a deadly Christmas Eve attack on Coptic Christians. AFP PHOTO / LOUISA GOULIAMAKI