Guatemala's Christian Democratic Party, one of the country's largest moderate political groups, has issued what its leaders consider virtually a final appeal for peace in that troubled Central American nation, calling on the military-based government to open the political process to all parties and ideologies.

In a statement released this week in Washington and scheduled to be announced at a rally in Guatemala City, the Christian Democrats appealed for an end to the pervasive militarism fostered by the conservative Army officers in power, and increasingly adopted by leftists looking for political, economic and social change there.

Although it has not yet reached the level of outright warfare that now exists in neighboring El Salvador and that tore apart Nicaragua last year, the polarization of Guatemalan society is rapid. If it becomes absolute, as few people now doubt, the result is likely to be a major civil war in Central America's most populous country. It is just south of Mexico's richest oil fields.

The appeal issued by the Christian Democrats, who party officials said have lost more than 25 leaders through assassination by death squads and other groups widely believed to be closely associated with the right-wing government, calls for the establishment of a National Peace Board.Through broadbased representation, the party hopes, it might begin to alleviate political tensions.

But at the same time, the statement notes that "evidently conditions do not exist to bring into being" such a board. The proposal is presented as if it were a last, and rather forlorn hope before a holocaust. "We leave the proposal on the table," the appeal said, "and we will continue promoting it, disposed to second whoever decides to take it and those who are actively convinced that dialogue can avert the deepening of the bloodshed."

Although Guatemala ostensibly enjoys an elected government, elections repeatedly are won by military officers and generally considered rigged. Civilian parties, most of which are denied legal recognition by the government, have effectively been prevented from presenting candidates in nationwide races. At the same time, large numbers of civilian political leaders, both centrist and center-leftist, have been murdered in recent years.

As a result, even Guatemalan moderates are now taking up arms against the government. While deeply suspicious of the leftist guerrillas now operating in the northern and central parts of the country, even some of the most moderate Christian Democrats have acknowledged the need for "self-defense" in the face of the frequent attacks they have suffered.

Guatemala has never seen anything quite like this before. In the 1960s there was a significant guerrilla movement, but it was almost exclusively Marxist and rooted in the eastern part of the country where violence resembling feudal warfare has long been endemic. Those guerrillas were eventually bought off or exterminated, with a loss of several thousand lives.

Now there is increasing evidence that the traditionally neutral Indians, who make up roughly half of the country's population, have begun joining forces with such groups as the Guerrilla Army of the Poor to find, at least, some sort of protection from government troops -- who have built a reputation for killing anyone suspected of guerrilla sympathies.