From the earliest days Christianity has been opposed to slavery. In his Letter to the Galatians, St Paul wrote: “As many of you that have been baptised in Christ, have put on Christ. There is neither Jew nor Greek: there is neither bond nor free: there is neither male nor female. We were all one in Jesus Christ.” Undoubtedly Christians have compromised with slavery — as with other social evils — in the course of history, but the orthodox Christian doctrine is one of liberty and equality.

The Christian belief was the inspiration in William Wilberforce’s long campaign to end the slave trade. His Bill received the Royal Assent on March 25, 1807, 200 years ago. That was the most important of all the great reforms of the 19th century; essentially it was a Christian reform, inspired by the Protestant conversion of Wilberforce himself. March 25 was the old New Year’s Day; it is also the feast of the Annunciation of Mary, the Mother of Jesus.

We live in an age when modernists regard religion with something approaching panic. It is like the Devil’s attitude to Holy Water. There was a comic example of Christianophobia in The Sunday Times yesterday. Michael Portillo, who used himself to be seen in Brompton Oratory, was hyperventilating at the idea of David Cameron going to church. “I worry,” he wrote, “because men of power who take instruction from unseen forces are essentially fanatics . . . I would be more reassured to hear that the Tory leader goes to church because that is what it takes to get a child into the best of state schools, not because he is a believer.”

Perhaps this neurotic response to Mr Cameron’s habit of going to church reflects Mr Portillo’s recognition that religion is again becoming an important influence on society. Many of the current news stories show that religion is back in public consciousness; for those who feel uneasy about religion, that is unwelcome.

Islam is, of course, the alarming religious issue that will not go away. In the 20th century the world failed to adjust to two major belief systems, nationalism and Marxism. Now we face a similar global challenge from Islam, which opposes Judaism in Israel, Hinduism in India, Buddhism in South East Asia, Christianity in Europe and America and modernism in the whole advanced world. We certainly cannot say that all religious influences are benign; al-Qaeda is a religious cult, but a perverted one.

Religion turned William Wilberforce into a Protestant saint, but Wahhabism has turned Osama bin Laden into a devil.

The rise of militant Islam in the 21st century is, however, part of a much broader phenomenon. In the United States there has been the extraordinary resurgence of fundamentalist Protestantism, sufficiently strong to win two presidential elections for the Republican Party. In Britain, an inflow of Catholics from Eastern Europe, particularly Poland, has revitalised the Roman Catholic Church, which now has the largest Christian congregation in the country. The worldwide Church of England has been divided by a battle of moral convictions. All of these religious movements challenge modernism, that popular mix of materialism, scientism and political correctness that had seemed to be carrying all before it.

The modernist attack on religion was based on the victory of science, and particularly of neo-Darwinism. Yet science was open to the same challenge as religion; it could explain only half the world. The scientists, or some of them, sneered at religion for being unable to explain the developments of nature. Yet science itself was unable to produce a science-based morality for society. Marxism attempted to create a scientific social order that ended in monstrous and bloodthirsty tyranny. Social Darwinism either meant eugenics and the slaughter of babies who were not thought fit to survive, or it meant nothing. The Social Darwinism of George Bernard Shaw, or indeed that of Adolf Hitler, has been rejected by mankind.

The world needs religion to address the moral issues. In the advanced societies it is these moral issues that now mock us. Europe and North America are hugely wealthy regions, but they are morally impoverished. Broken families, drugs, booze, youth gangs, crime, neglect of children and the old, the sheer boredom of shopaholicism, terrorism, the inner-city slums, materialism itself, are all the marks of a global society in decline. Societies can be judged by their care for children. Social education must start in the family and must have a moral basis. Children need to be taught to distinguish between right and wrong. A recent report by Unicef showed Britain as 21st out of 21 advanced countries in the welfare of children; our national failure is a shame and a disgrace.

In 19th century England, the revival of Christianity provided the basis for a century of social reform. The religious revival spread across all the Christian churches; in the Church of England there was the Evangelical movement as well as the High Church movement. The Roman Catholic Church attracted thousands of new converts. The Methodists and other Nonconformists devoted themselves to the welfare of the poor and the working class. The Salvation Army took its trumpets into the pubs and slums and offered a new hope.

The 19th century was an age of social reform based on religious revival and the Christian faith. The 20th century was an age of religious decline and of accelerating decline in social cohesion as well as in faith. “Ill fares the land, to hastening ills a prey/ When wealth accumulates and men decay.”

These are lines from Oliver Goldsmith’s moving poem, The Deserted Village in the 18th century. If they seem to apply to our modern societies, religion is not the problem; it is the only possible remedy.

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