ANY HOPE THAT SOMETHING good will come out of President Reagan's Latin American piligrimage rests on the slim likelihood that he will listen to Colombia's President Belisario Betancur on guerillas.

President Betancur, elected last June, has an idea that Reagan will find utterly novel: you forgive them, bring them into the political process. He has signed an act of amnesty which will go into effect next January.

Betancur, a former journalist and veteran conservative politician, is unique among South American leaders, who in the main, subscribe to the notion that the only way to deal with dissidents is to exterminate them.

If Reagan would be persuaded to the Betancur view and apply it to El Salvador, an end to the current slaughter -- in the first two weeks of October alone, 68 civilians were murdered for no special reason -- might be achieved.

Betancur might also be able to pry open Reagan's mind to the possibility of getting along with the Marxist regime in Nicaragua. The previous government of Colombia supported the Reagan approach to Nicaragua, which is that it is an offense against nature and not to be tolerated.

Colombia and Nicaragua were involved in one of those inevitable Latin-American disputes over the jurisdiction of an island. But Betancur seems willing to acknowledge Nicaragua's right to exist, and has joined with Venezuela and Mexico in an appeal for some negotiations -- an alternative he plainly considers preferable to the $19-million covert-action campaign our government has never denied undertaking.

Betancur also supports Venezuela and Mexico in their call for negotiations in El Salvador between government and guerrilla forces. Reagan finds the prospect of such talks extremely distasteful. The regime in El Salvador goes on kidnaping and murdering members of opposition parties, while the State Department natters about "bringing a broad spectrum of the forces and factions into a functioning democratic system."

The theme of Reagan's trip is to "promote democracy in the area." That theme goes off the rails when he arrives in Honduras, by far his most provocative stop. Honduras is indeed trying to be democratic, but we are doing our best to militarize it for purposes of our own. Somebody in the administration got the brilliant idea of using Honduras as a staging area for an assault on Nicaragua, manned by former Somoza guardsmen .

Some more observant Hondurans have noticed that while what we have in mind is the destabilization of Nicaragua, the net effect of our ten-fold increase in military aid could end up destabilizing Honduras.

On the eve of the visit, the Hondurans announced the suspension of joint U.S.-Honduran military maneuvers -- "before or after President Reagan's visit." Some took this to mean that the doves had prevailed, but the State Department said promptly that the maneuvers were not dead but sleeping -- "postponed but not canceled."

Whatever the maneuvers' future, the Reagan stop will doubtless be interpreted throughout Latin America as an implicit endorsement of the proxy war his hosts have embarked on in our behalf.

If Honduras is the most egregious place he visits, the president's most controversial visitor will be Guatemala's President Efrain Rios Montt of Guatemala, who seems to be going for the hemispheric title in human rights violations.

The Americas Watch Committee has issued a timely report about Rios Montt's "total war against insurgents -- those who are not with the government are shot." Thousands of Indians have been killed by government forces. The State Department attests, as it usually does, that "human rights progress is being made." Human rights groups protest that the massacres have been moved from the city to the countryside.

The president is spending most of his time in Brazil, which has just democratically elected a government. Nicaraguan ambassador Francisco Fiallos hopes that Reagan will listen to its new president. Brazil's new president, Gen. Joao Figueiredo shares the Colombian opinion that to be democratic is to be more than non-communist.

Reagan is hoping to mend fences with Latin-Americans who were outraged by our support of Britain in the Falklands war. To that end, he apparently acceded to the idea of visiting Argentina's president, Reynaldo Bignone at Brazil's border. To the great relief of human rights advocates, the general turned the president down. Recently, in Argentina, 400 unmarked graves were found. The military refuses to identify the dead unless it is spared responsibility for them.