``We turn to the people and call on them to demonstrate against efforts to make Greece a non-religious country,'' Archbishop Christodoulos said. ``The faithful public oppose this attempt to push religion into the margins.''
Christodoulos said protest rallies will be held in Athens and the northern port of Thessaloniki later this month.
The decision, announced after a nine-hour meeting of the church hierarchy, was the latest salvo in an important showdown between the Socialist government and clergymen and their supports.
Premier Costas Simitis says religion will be deleted from ID cards to conform with privacy protection laws. Earlier Tuesday, Simitis turned Christodoulos' offer for talks to seek a compromise.
Government spokesman Dimitis Reppas said he was ``shocked and surprised'' by the church's decision, but insisted there would be no change in policy.
More than 90 percent of Greeks and baptized into the Orthodox Church, which represents Greece's official religion and wields considerable influence in public life.
Church supporters say keeping religion on ID cards is an important symbolic gesture that recognizes the role of the Orthodox church in preserving Greek identity during years of foreign domination and occupation.
But the government and leaders of non-Orthodox faiths in Greece say the measure is outdated and breeds prejudice.
The church-sponsored rallies are planned for Thessaloniki on June 14 and in Athens on June 21.