FEW would doubt that the most important theological encounter for Christians today is with Islam. Prominent Anglicans have long been ahead of the game in this. The former missionary Sir Norman Anderson lectured in Islamic Law at Cambridge and at SOAS. Bishop Kenneth Cragg introduced Islam to a Christian readership in The Call of the Minaret (1956).

Today, the Cambridge Interfaith Programme runs courses and promotes research into Islam and other religions. The aim of such encounters is not theological agreement, but a respectful entering into a faith that is related historically to our own. Yet little of this percolates through to the average congregation. This is a shame, because the one thing a real encounter with a passionate believer from another faith should produce is a deeper understanding of one's own faith.

My first such meeting was when a young Muslim in a café in Mombasa presented me with a green-bound copy of the Qur'an in Swahili, and asked me whether I had ever felt that there was something missing from my life. His upfront approach reminded me of Evangelical Christianity.

As I reflected on our meeting, I realised that, for Christians, there is no option other than to recognise that the God proclaimed in the Qur'an is the one we call the Father of our Lord Jesus Christ. We are not talking about "other gods". Nor are we into a clash of civilisations. Thank God that British far-right campaigners realise that the contemporary Church offers zero support for a nationalist Christian agenda.

Christianity and Islam have been closely interlinked for centuries. We owe to Islamic translators our knowledge of Aristotle and the tradition of natural theology which Thomas Aquinas bequeathed to the West. What baffles me is why so few contemporary Christians are interested in theology. Why do eyes glaze over at the mention of the Trinity, and why are we faintly embarrassed by the Creed?

A deepening encounter with Islam could sharpen our understanding of our faith, at a time when it is in danger of dissolving into well-meaning moralism, tinged with sentimentality. Visits to Egypt over the years have taught me the spiritual potency of lay theology. I have debated fifth-century Christology with a Coptic Christian taxi-driver, whose grasp of what was at stake was superior to that of the ordinands I used to teach. This is because it really mattered - just as the content of their faith mattered to the driver's Muslim counterparts.

The Revd Angela Tilby is Diocesan Canon of Christ Church, Oxford, and Continuing Ministerial Development Adviser for Oxford diocese.