For the first time in the many years of rebellion in southern Mindanao against the government of President Ferdinand Marcos, the Roman Catholic Church and its clergy have become the target of violent attacks.

Church leaders in Asia's only predominantly Catholic country are unclear as to why the religious institution has been singled out as a new target of the violence that has killed and maimed hundereds in the past month alone. But an uncomfortable feeling prevails among church leaders that the attacks signify the breakdown of authority on an island racked by violence.

At the same time, priests are concerned that attacks against the church will continue, now that they have begun. One American Maryknoll priest, the Rev. Tom O'Brien, said in Davao City, "Now that they are bold enough to kill priests, it is inevitable more will follow."

The church fears that it continually will be caught in cross fire between the right and left, as well as burgeoning armed groups that represent varied interests.

Military investigators have no leads on who was responsible for two grenade explosions in the San Pedro Cathedral in Davao City during Easter services on April 19 that killed 16 people and wounded 171 others, nor in the case of the Rev. Godofredo Alingal, a Jesuit priest slain April 13 at Bukidnon, on nothern Mindanao.

In March, Bishop Pedro Dean was seriously injured in an ambush in the neighboring province of Davao del Norte, in what church sources in Davao City say was a case of mistaken identity by the communist New People's Army.

Western Mindanao has seen an eight-year-old Moslem rebellion, spearheaded by the Libyan-backed Moro National Liberation Front, that has taken 60,000 lives on both sides.

The rest of Mindanao has been infiltrated by bands of communist rebels during the last decade.

A group called the "Lost Command," composed of dismissed soldiers, reportedly has been robbing farmers and killing suspected communists.Some of these ex-soldiers now form the private armies of local politicians and big businessmen, protecting them from communist harassment.

The government denies charges by church and local officials that the Lost Command is under tacit command of the military.

Defense Minister Juan Ponce Enrile recently told foreign reporters: "We have been hearing about the Lost Command since 1966. I don't know whether they exist."