The church hopes it can force the government to revoke a decision eliminating the religion entry from state identity cards. It would like to collect nearly 5 million signatures--about half the total population--to force a referendum on the issue.
But the showdown resonates far beyond just ID cards. It represents an important crossroads for Greece: whether the nation can adopt European Union norms or remain under the influence of clergymen who are highly suspicious of the EU and the influence of the West.
"We will continue our struggle for Greece to remain a Christian state, as we knew it and want to live it," Archbishop Christodoulos, the firebrand leader of the church, said earlier this week during a pilgrimage to Jerusalem. In June, he led huge rallies against the ID changes in Athens and the northern port of Thessaloniki.
While most Greeks vacationed in August, church printing presses worked overtime churning out millions of ballots that will be carried door-to-door as part of their campaign.
Christodoulos plans to formally open the signature drive Friday, the first day of the ecclesiastic new year. It will end on March 25, the day Greece celebrates its early 19th century war of independence from Ottoman Turkish rule. He held a meeting with senior clerics on Thursday to iron out the final details.
By that time, however, the new identity cards should be in circulation. The government said it will begin issuing the new cards in October.
Premier Costas Simitis has said the issue of including religion on the ID cards is closed for the government, arguing it abolished the religion entry because it ran counter to Greece's modernization efforts and European outlook.
Human rights groups and the country's religious minorities, including Jews, Muslims and Roman Catholics, also welcomed the decision. They claimed the old ID cards allowed religious discrimination.
The government fears the church's signature campaign could deeply divide Greece, where more than 97 percent of the native-born population is baptized into the Greek Orthodox Church but opinion polls show a near even split on the ID issue.
President Costis Stephanopoulos warned the "rift has to stop because it can only do harm."
But many Orthodox church leaders are wary of the government's drive to bring Greece into the mainstream of the EU. They see it as a threat to the Christian Orthodox character of the nation and possibly the stirrings of an eventual separation of church and state in Greece, where Greek Orthodoxy is the official religion.
"This war is being waged between the sons of darkness and the sons of light. We believe wholeheartedly that we belong to the sons of light," Christodoulos said.