The 11-day-old cease-fire between Moslem rebels and government troops is holding in the southern Philippines, but lasting peace is still uncertain.

In a just-concluded trip to the area, I found a strong Christian backlash against the peace agreement that was worked out in Tripoli, Libya, between the Philippine government and the Moro National Liberation Front - the rebel organization. The agreement prepares the way for some autonomy in 13 provinces in the southern Philippines.

One Christian laborer from Cotabato told me: "They should have let the fighting go on. We will watch this peace, but we will keep our guns." The mayor of Zamboanga City, Joaquin Enriquez, said: "The people are apprehensive about the peace agreement."

The majority of the people in the southern Philippines are Christian and the peace agreement signed in Tripoli Dec. 23 appears to give autonomous control of the region to the Moslem rebels.

The Philippines government has prohibited publication of the terms of the peace agreement and banned its dissemination. This had led to wild speculation as well as concern. One young Christian woman in Zamboanga said: "The news is that the Moslems will be in control. I don't want to be ruled by Moslems. I'll move back" to the Christian north.

The rebel organization, well aware of this backlash, said in a recent newspaper: "We appeal to our brothers and sisters of the Christian faith not to entertain undue apprehension about the grant of the autonomous government."

Mayor Enriquez said he has met twice with President Ferdinand Marcos to discuss the backlash and has been told to try to reassure his Christian constituency. According to the mayor, the message from the presidential palace was: "Tell them not to worry - the president won't sell them down the river."

But the mayor is worried. Marcos gave him a copy of the peace agreement that did little to allay his fears.

He finds especially worrisome provisions in the agreement that: "special the moslems;" "the Moslems shall have their own administrative system;" and "a legislative assembly and an executive council shall be formed in the areas of the autonomy for the Moslems."

Enriquez says Marcos assured him and his fellow governors and mayors of the region that the agreement was not final, pending further talks in Tripoli beginning Monday, and that any questionable portions were probably due to a mistranslation from Arabic.

Turkish former parliamentarian Cihad Fethi Tevetoglu, an official of the Islamic foreign ministers' conference who attended the Tripoli talks, said Libyan leader Col. Muammar Qaddafi coaxed Marcos into a compromise with promises of oil and aid. Now Qaddafi can tell other Middle East states that he can solve world problems while they squabble among themselves, said Tevetoglu.

Now, it is felt here, the reputations of Qaddafi and Marcos rest on the outcome of the coming round of talks in Tripoli.Marcos' negotiators, observers say, will have to display the highest degree of political acumen and diplomatic finesse to satisfy the rebels, the Islamic nations, and the Philippines' Christian constituency.