Cardinal Alfonso López Trujillo was the Vatican’s defender of family values for two decades, serving under two popes and marshalling arguments against divorce, contraception, abortion and other challenges to Catholic orthodoxy.

He was an intellectually sophisticated conservative, who had studied sociology and anthropology, with a particular interest in Marxism, and he deployed his knowledge to reject liberal ideas by appeals to common sense and self-interest, rather than just demanding obedience to authority.

Alfonso López Trujillo was born in 1935 in the Colombian provincial town of Villahermosa, in Tolima department. His family, prominent Catholics, later moved to Bogotá. His father was in charge of the general accounting office of the Government, and one of his uncles was a minister of state.

After school López Trujillo studied at the National University in Bogotá before studying for the priesthood at the archdiocesan seminary. An exceptionally bright student, he was sent to Rome, where he completed a doctorate in philosophy at the Angelicum and also completed additional studies in theology, sociology and Marxism.

He was ordained in November 1960, and returned to Bogotá, where he began a rapid ascent through the church hierarchy. In 1968 he was made pastoral co-ordinator of the archdiocese and he attended the second general conference of the Latin American Bishops’ Conference (Celam) in Medellín. The meeting was a huge boost to liberation theology and its adherents. López Trujillo opposed this understanding of the gospel, believing that it was trying to replace salvation by Jesus with class struggle.

After teaching for four years at the seminary he was appointed vicar-general of the diocese of Bogotá in 1970, and the following year he was made bishop of Boseta and auxiliary of Bogotá, at 36. In 1972 he became general secretary of Celam and organised its third general conference, in Puebla, Mexico, in 1979. In that same year he was appointed Archbishop of Medellín and became president of Celam. He was the youngest cardinal when he was proclaimed in 1993. In 1990 he had left Colombia for Rome, where the Pope made him president of the Pontifical Council for the Family, and in 2001 he became one of ten cardinal- bishops, with the title of Bishop of the Suburbicarian See of Frascati.

López Trujillo was a resolute opponent of the liberation theology that swept through the Latin American Church in the 1970s; he regarded the “preferential option for the poor” espoused by the liberation theologians as a political rather than spiritual movement.

In his role as head of the Vatican’s family department, he acted as the public defender of marital fidelity, and articulator of the view that abstinence was the only sure defence against the spread of HIV/Aids.

With European society and the Catholic Church increasingly at odds over sexual ethics, López Trujillo never minced his words. He told a meeting of the Guild of Catholic Doctors in London that the UN conferences on population in Cairo in 1994 and on women in Beijing in 1995 had attempted to introduce “a new sort of morals”. When, in 1997, the Vatican initiated the process to beatify Óscar Romero, the Archbishop of San Salvador, who was assassinated in 1980 while celebrating Mass, López Trujillo opposed it on the grounds of Romero’s liberation theology sympathies.

López Trujillo returned to the headlines in 2003 when he said on the BBC Panorama programme Sex and the Holy City that condoms did not prevent Aids because the virus was small enough to pass through them. But, in an interview soon after with Vatican Radio, he cited studies that supported his view.

He also asserted that condoms were being used by rich countries as an instrument of what he termed “contraceptive colonialism”, to impose birth control on poor ones. But he often seemed to be fighting a losing battle: by that time Brazil, the country with the world’s largest population of Catholics, was leading the way in combating Aids with a government programme of free condom distribution, including to schoolchildren.

Legal reforms in Spain in 2005 to permit same-sex marriage and adoption provoked another attack from López Trujillo, who said they were “another step towards the total destruction of the institution of the family, the most valuable heritage of all peoples and all humanity”. The adoption of a child by a same-sex couple would, he said, jeopardise the child’s future and amounted to an act of moral violence against the child. He called for Catholic professionals and officials to exercise their right to conscientious objection in such cases.

As well as keeping up with the latest research, López Trujillo’s council conducted its own programme of publications. In 2003 it completed one of his pet projects, a lexicon of what he regarded as ambiguous terms in discussions of life and family matters. The lexicon said that terms such as “gay marriage”, “reproductive rights” and “emergency contraception” were euphemisms that denied the natural truths about sexuality, marriage and the dignity of human life.

After being confirmed in his post by Pope Benedict XVI in 2005, López Trujillo expressed his admiration for the Pope’s approach to family issues. The Pope addressed these issues in broad terms, he said, using philosophical and anthropological arguments as well as church teachings to make his points. Humanity rejected the fundamental laws of nature at its peril, he added.

In the following year López Trujillo deployed these arguments to challenge stem-cell research, threatening scientists who engaged in it and politicians who passed laws permitting it, with excommunication. “Destroying human embryos is equivalent to an abortion. It is the same thing,” he told Famiglia Cristiana, the Catholic weekly magazine.

López Trujillo remained a controversial figure in Colombia long after he had departed its shores. In 2005 a leading newspaper columnist, María Jimena Duzán, accused him of maintaining “good relations” with the notorious drug baron Pablo Escobar while he was a member of the legislature and was running a low-cost housing programme in Medellín. The Cardinal denied any connection, saying he had always been a firm opponent of drug traffickers, who had made two attempts on his life.

Despite his unpopularity among some liberal Catholics and the attacks he came under in the media, López Trujillo never wavered in upholding traditional Catholic teaching. He once remarked about the role of the Pontifical Council for the Family: “As the Pope would say, these are decisive battles, and we want to be in the middle of them.”

López Trujillo was a member of four Vatican Congregations: the Doctrine of the Faith; for the Causes of Saints; for Bishops; and for the Evangelisation of Peoples, as well as the Pontifical Commission for Latin America.

Cardinal Alfonso López Trujillo, President of the Pontifical Council for the Family, was born on November 8, 1935. He died of cardiac arrest after a short illness on April 19, 2008, aged 72