The Catholic Archbishop of Washington DC has defended religion's role in public life as "essential" and insisted "we'd be a mess without it".

In a column for the Washington Post, Cardinal Donald Wuerl said that despite challenges, "religious faith and its moral perspective are not only still valid but essential aspects of a truly good and just society".

He argued that without religion's understanding of the value of human life, "all human life becomes vulnerable". Religion, he said, insists there is an objective reality to judge decision against.

"To speak out against racial discrimination, social injustice or threats to the dignity of human life is not to force values upon our society but rather to call it to its own legacy of long accepted, moral principles and commitment to defend basic human rights," he wrote.

"Religion and Gospel values are not optional extras in the effort to build the common good, but essential. Science and technology have brought mankind enormous progress, but science and technology by themselves will not save us.

"At the heart of the contribution of the Church to the public square and therefore public policy is the recognition that it is not by bread alone that we live."

Wuerl's defence comes after the Catholic Church in the US has been at the mercy of a series of revelations surrounding child sex abuse by clergy that have damaged its public role.

Wuerl, who has been an archbishop since 2006, has a "national reputation for zero tolerance of priests who molest minors" according to the Pittsburgh Post-Gazette. In 1988 as a priest in Pittsburgh he accepted a dinner invitation from a family who was sueing the diocese for abuse by a priest. Although his lawyers advised against it, Wuerl's attendance led to the resolution of the case and the eventual imprisonment of the priest in question.