A golden thread links Pope Francis to Oscar Romero, the murdered archbishop whose beatification the Pope ordered to take place last weekend, to the rapturous acclaim of the people of El Salvador and the wider world.
The thread is that of liberation theology, the movement that swept through Latin America, and then other parts of the world, 40 years ago. It maintains that the Gospel contains a preference for poor people -- and insists that the Church has a duty to work for political and economic as well as spiritual change.
Conservatives in the Catholic Church do not like this. They have taken to asserting that Romero was not a liberation theologian. There is an irony in that, for they had spent the previous three decades blocking Romero's path to sainthood by arguing the opposite. Then they said that to canonize the murdered cleric would effectively endorse liberation theology too.
Conservatives saw this radical pro-poor movement, at the height of the Cold War, as a Marxist Trojan horse that would allow communism into South America through the back door. Its followers saw it as the words of Jesus in action.
In the years that followed, the mainstream Catholic Church took on board many of the insights of liberation theology. But conservatives in the Vatican and in the Latin American hierarchy worked behind the scenes to counter its influence -- and block any attempts to move Romero along the path to becoming a saint.
There is an effective answer to these machinations and manoeuvrings. It is the one given by the man who is indisputably one of the founding fathers of liberation theology, Leonardo Boff, a former Franciscan friar who left the priesthood after the Vatican ordered him to a period of "obsequious silence" under the conservative papacies of John Paul II and Benedict XVI.
When asked if Pope Francis was a liberation theologian, Boff gave an answer that would apply as aptly to Romero. "The important thing is not whether he is for liberation theology but [whether he is] for the liberation of the oppressed, the poor and the victims of injustice. And that he is without question. Pope Francis has lived liberation theology."
Oscar Romero lived it too. He was not a theoretical theologian. He stood unflinchingly by the poor -- and died for it.
He began as a conservative but events changed him. He became archbishop of San Salvador in 1977 at a time when community leaders and priests who spoke out over the nation's extreme and pervasive poverty were being killed by death squads in the pay of the country's exploitative coffee barons. Rural peasants and urban demonstrators were massacred on the streets by the army. Political prisoners were kidnapped and tortured. Churches were desecrated, and diocesan radio stations and newspapers bombed.
Romero spoke out against all that. It made him, to the repressive elite, a communist in a cassock. He was shot dead at the altar.
The ordinary people swiftly acclaimed him a saint, calling him St. Romero of the Americas. But conservatives in the Vatican and among the Latin American bishops stalled the canonization process for Romero for more than three decades. Eventually they ran out of excuses to keep blocking recognition of his transparent martyrdom. So they began to insist he was not really a liberation theologian. It was a blatant attempt to separate the martyr from the theological movement he embodied.
All this had deep resonance for Pope Francis who saw in Romero a model for his own spiritual journey. Like Romero, he had also begun as a conservative. As leader of the Jesuits in Argentina in the 1970s, Francis had seen it as his job to stamp out liberation theology. But events changed him too.
His authoritarian leadership of the Jesuits ended with him being sent into exile after presiding over a deep and bitter split inside the order. In those two years of exile, he underwent what he has since called "a time of great interior crisis" and emerged with a much more consultative leadership style.
As Bishop of the Slums in Buenos Aires, his prolonged contact with poor people brought a change in him. Before he had seen them as victims in need of charity. Now he began to see them as people who needed help to take charge of their own lives. He began to back self-help groups, co-operatives and unions -- exactly the kind of work he had banned among Jesuit liberation theologians 20 years before. "Experiencing the life values of the poor transformed his heart," as one of his shantytown priests, Fr. José María di Paola, put it.
When Argentina went into a massive financial crisis in 2001, with the biggest debt default in world history, half the country's population was plunged below the poverty line. The resulting hardship made Francis see that economic systems, not just individuals, could be sinful. He began to use the language of liberation theology in his castigations of the government and the international financial system with its austerity "medicine" of cuts to the services on which the poor relied.
He has continued that language as Pope, with fierce criticisms of global capitalism in the two years since he took office. And he has rehabilitated liberation theology by inviting its key exponents to the Vatican and into dialogue with him on his forthcoming major document on the environment. Rome's key doctrinal watchdog has declared that liberation theology should "be included among the most important currents in 20th century Catholic theology."
Oscar Romero is therefore not simply, for Pope Francis, a man whose courageous death needs to be honored. He is a priest whose life stands in testament to the kind of Catholicism preferred by a pope who declared within days of his election that he wanted "a poor Church for the poor."
Romero is an exemplar for Francis as he launches on what may well be a defining period in his pontificate. The next six months will bring three key events. The Pope's long-awaited encyclical on the environment and climate change is due next month. Then come official visits to South and then North America. And then comes a Synod in Rome that could bring changes to the approach of the Catholic Church to issues like divorce and homosexuality.
Romero was a man who was at once utterly orthodox and yet utterly radical. That is the model Pope Francis seems to be setting for himself.
Paul Vallely is the author of Pope Francis - the Struggle for the Soul of Catholicism, to be published by Bloomsbury in September.