HAVANA — OSWALDO PAY'A SARDINAS is a Cuban radical. ``Radical but not violent. The truth,'' he says during a clandestine interview, ``is radical.'' Mr. Pay'a works for the state, as does everyone in Cuba, as a medical technician in a Havana health clinic. Outside of work, as the general coordinator of the Christian Liberation Movement, Pay'a risks imprisonment by advocating freedom of speech and religion. ``In Cuba, there is oppression, a culture of fear. The sovereignty of the people has been lost,'' Pay'a says. ``If you call it `Castroism,' `socialism,' `communism,' or whatever name you give it, this reality has to change towards democracy.'' Currently, Pay'a is quietly collecting signatures for a referendum on allowing democratic elections. Pay'a's organization started in 1988. It grew out of a Roman Catholic discussion group that used to publish a newsletter, ``People of God.'' But as its messages became more critical, more daring, the church gave in to government pressure and dropped its support for it. Pay'a claims a nationwide membership now from most Christian denominations but refuses to divulge total figures for fear of exposing supporters to police harassment. There are few signs of political change in Cuba. But diplomats here generally agree, Fidel Castro is loosening restrictions on Cuban churches. One might question whether Pay'a's group is preaching to the converted. In December, for the first time under President Castro's 31-year rule, Protestant churches were allowed to produce and air a half-hour Christmas radio program. Cuban officials have said regular religious television and radio broadcasts may begin in March. Last June, for the first time, Castro raised the possibility of Communist Party membership for church members. Indeed, since 1985, Castro has slowly moved toward accepting religion as part of this socialist state. The Ecumenical Council, which includes representatives from 24 of 56 Protestant denominations, but not the Catholic church, has expressed support for Castro's recent efforts to ``perfect socialism.'' But Pay'a and outside observers are skeptical of Castro's motives. ``He has eased a little. But it's a strategy [through the Ecumenical Council] to divide the Protestants and Evangelicals from the Catholics. To divide and co-opt the ones you can and to isolate the ones you can't,'' says a Western diplomat. ``The Ecumenical Council is not representative of the Evangelical churches,'' asserts Pay'a. ``I identify deeply with my Evangelical brothers, but they are being politically manipulated.'' Pay'a fears Cuba's worsening economic situation may soon produce a violent, political crackdown in the face of growing dissatisfaction with Castro's rule. He also warns the United States ought to be wary in dealings with Cuba in the coming months because Castro will use any provocation to shift people's attention away from domestic problems and blame the US. For these reasons, Pay'a says, the situation is urgent. He's talking with foreign journalists ``for international moral and prayerful support.'' And he's pushing a platform that not only advocates religious freedom but calls for dramatic political changes to attain the goal. On Nov. 20, he delivered a letter to Cuba's National Assembly calling for a referendum on reforming the constitution to allow democratic elections and amnesty for political prisoners. He also proposes a national dialogue, including Cuban exiles, about the reforms. The dialogue would be followed by free, democratic elections of the National Assembly, which the government will cede power to. ``This is the first concrete project that allows people to visualize the possibility of peaceful change,'' Pay'a says. Apart from threats by the security police, the letter (also sent to the government newspaper Granma, but not published) has provoked no official response. But as members of the Christian Liberation Movement have begun collecting the 10,000 signatures (``We now have several hundred'') needed to legally invoke a referendum, Pay'a says the government has ``panicked.'' ``We've received phone calls from security police saying, yes, this is legal but we're not going to permit it.'' The police, says Pay'a, are threatening to substitute false signatures on the documents when delivered and then prosecute the activists for fraud. Last March, Pay'a and two other members of the Liberation Movement were detained and questioned by security police for 40 hours. His neighbors are questioned regularly about his activities. And his house is frequently watched. The 38-year-old father of two toddlers is concerned for the safety of his family. But he's also concerned about their future. ``We don't believe in political change through violence, attacks, military coups, or foreign intervention that leaves power in the hands of the people,'' says Pay'a. His group is not pro-US. It is not a human rights group. It is not necessarily anti-communist, nor even anti-Castro, he says. But it is looking for a change. ``We want the people of Cuba to recover their sovereignty ... their capacity to decide and assume their own future.'' -PATHNAME- /usr/local/etc/httpd/plweb/DBGROUPS/paper/database/tape/91/mar/week10/dcuba.