"So we are ambassadors for Christ, God making his appeal through us, be reconciled to God".

This is a great day of celebration for the whole nation. In this service, we give thanks to God for the Christian roots of our land; for the part which the Gospel of Jesus Christ has played in the formation of our people. And it is a story worth celebrating, of the coming of learning as well as the renewal of the Church. There can be no doubt about the blessings which Christianity has brought. Nevertheless, it is a history which is littered with tragedy, and division, the results of which remain with us. But today we can unite in thanksgiving that the Gospel continues to inspire us, to challenge us, to draw us closer to one another, and it continues to be proclaimed faithfully up and down the country in churches, in halls and in the market place. It is wonderful to be able to welcome such an array of people from all walks of life to the Cathedral this morning, but especially my brothers and sisters who are leaders of other churches. I greet in particular Cardinal Hume, Archbishop Gregorios, the Apostolic Nuncio, Archbishop Luigi Barbarito, Bishop Aarflot, the Primate of the Norwegian Church, Dr John Reardon of CCBI and other representatives of the Free Churches. Today in a place so closely associated with the mission of St Augustine we celebrate our common heritage.

I am also very glad indeed to be able to join in the welcome to pilgrims who have journeyed from Rome in the steps of Augustine, and those who will continue the journey through these islands towards the city of Derry, founded by St Columba. As we all know, Columba, another great sixth century missionary, died in 597, and, together with St Ambrose, St Martin of Tours and St Ninian, all of whom are also remembered this year especially, they give us a wonderful picture of what it might mean to be Ambassadors of Christ.

So what do we learn from these great missionaries about our calling to be Ambassadors for Christ?

Some of you will, from time to time, like me, have reason to call upon one or other of Her Majesty's Ambassadors abroad. For me, it is invariably a great pleasure. What is the first thing that strikes one on entering an Embassy compound? There is always a Union Flag flying, and prominently displayed near the entrance of the building is a photograph of HM The Queen. There can be no doubt about what this building is, and whom the Ambassador represents. However warm the welcome one receives in a strange place, it is a comfort to know that the Ambassador is there, and I have no doubt that nationals of other countries have similar experiences when they visit their own Embassies in this country.

I am struck by Bede's account of Augustine's entry into Canterbury, faithfully recreated in this Cathedral this morning. He, and his party of monks, entered bearing a Cross, a Book of Gospels and an icon of Christ. There could be no doubt, in this foreign land, about whose Ambassador he is. Augustine was not by nature a courageous or heroic man. Gregory the Great who commissioned him was of much greater stature in that sense. But terrified as Augustine was by the awesome responsibility entrusted to him to carry the Gospel to the pagan and barbaric English, he persevered. The success of his mission is a wonderful testimony to how we all, with all our weaknesses, are used, by the grace of God, in his service. Columba, too, when he left his native Ireland in a coracle, carried nothing with him but a Bible. He had no idea where he might land, but he was confident that the Word of God was sufficient passport. There is something extraordinarily noble, extraordinarily courageous, and extraordinarily biblical about these pictures. Remember Abraham, uprooted and sent off with nothing but a promise. Remember the Apostles, sent out two by two, taking "nothing for their journey except a staff; no bread, no bag, no money in their belts" (Mark 6:8). Remember the missionary journeys of St Paul, the wandering of St Francis, and the wonderful faith of the 18th and 19th century missionaries who set out for unknown lands with a Gospel to proclaim, and no certainty that they would even survive. And many did not.

How that simple and faithful courage contrasts with terrible tangles in which the Church can get caught up. Many of you will know the famous painting by Hans Holbein, "The Ambassadors". Two fine and sympathetically painted men, one a bishop, rest on a table laden with symbols of the new learning, and human achievement. An enigmatic presence across the lower foreground is a distorted human skull, reminding us of our mortality; and in the top left hand corner is a partly-obscured crucifix. It is, of course, a painting of its time, which, in the midst of the European Reformation, was hardly apolitical. Yet it is not cruel. It is simply a timely reminder of how easily the faith can be submerged by the attractions of a worldly life and wisdom.

St Augustine reminds us of the need to be wholeheartedly focused on God, for he is our message, he is what we bring before the world. But if we must be transparent in our lives, the way we tell the story is important too. Ambassadors are in the business of crafting words, of persuading others of their case. It was said by one 17th century diplomat and poet that:

"An ambassador is an honest man sent to lie abroad for the good of his country." (Henry Wootton)

A cynical view, perhaps, and I am sure an anachronistic one too. But we have been reminded already in our service of the encounter between Augustine and King Ethelbert:

"Your words and promises are fair indeed," says Ethelbert, "but they are new and strange to us. I cannot accept them, but since you are sincere in your desire to instruct us in what you believe to be true and excellent we will not harm you."

The capacity we have to wound one another by the words we use is obvious, and we see so many examples around us - between husbands and wives, between parents and children, teachers and pupils, politicians of one colour and another, between Christians of different traditions. It is nothing new, yet it is a perversion of our God-given diversity that so often we try to win our case by a cutting word or a cruel jibe. That we are different, that we disagree, that we seek to make our case in our own way is of the nature of things. But, at least as evangelists, our message is a positive one, it is an exciting one, it is a story which commends itself to listeners. We believe it to be "true and excellent" and our words must be a witness to that.

Thirdly, however, Embassies, or Ambassadors, were, of course, originally sent from one court to another to craft treaties, to create peace between nations. That is, in short, the task with which we are commissioned. We are messengers of peace. We are, to use St Paul's words, entrusted with the message of reconciliation. And, here again, St Augustine challenges us because he calls to us across the centuries from the one, undivided Church of Jesus Christ. We know that Augustine was not exactly diplomatic in acting so imperiously when he met up with the British bishops at Aust. However, at least within a few generations the Church he represented and the Celtic Christians whose parallel mission was so crucial to the story, were able to reach an historic agreement that was to hold until the 16th century divisions of Western Christianity. Can we, successors of Augustine's mission in this land, reach for a vision of reconciliation that will lead us to the unity which we know to be the will of God? Perhaps such a vision will focus on a fresh estimate of one another's churches, orders and mission. Perhaps it will be built on new ways of working, sharing in common worship, witness and service. Perhaps it will be anchored in a realisation that what we have in common vastly outstrips all that divides, set as we are in a society which is careless about Augustine's faith, let alone the denominational differences which separate us. If in Augustine's coming we savour our origins, in his mission can we find our unity?

These words echo the thoughts of his Holiness Pope John Paul II in his message for the Feast of St Augustine which has generously been passed on to me by His Eminence, the Cardinal Archbishop of Westminster. The Pope writes:

"I pray that the memory of your common ecclesial heritage will lead all Christ's disciples in Britain to ever increasing ecumenical co-operation, in a constant search for that fidelity to God's grace which alone can lead to the unity without seam or tear, which the Lord wishes for his followers."

That must surely be our desire too.

In a few minutes we shall be commissioning the pilgrims who will be travelling from here to Londonderry. They will be our Ambassadors. Some of them will be visiting Aust. It is a place at which the message of reconciliation will be uppermost. Other pilgrims will be visiting some of our inner and outer city areas - in London, in Birmingham, in Middlesborough and Newcastle and other places as well. These are areas where people have been left behind, where some feel alienated. The message of St Paul "If anyone is in Christ, he is a new creation", needs to be heard, and lived there, as it does in Westminster and Canterbury and elsewhere. Some will visit Iona, a place of prayer which has focused on justice and peace. And the pilgrims will re-unite in Northern Ireland, and spend time together with the Corrymeela Community as they celebrate the Feast of St Columba, and where could there be more urgent need for that ministry of reconciliation than in Northern Ireland and a more potent example of gentle, sacrificial peace-building over many years than Corrymeela?

Augustine arrived 1400 years ago with a message which today we celebrate. It is the same message which St Paul preached before him: "We are ambassadors for Christ ... be reconciled to God".

It is a message to the world, to find in Christ, the Son of the Living God, who renews and recreates his people. It is a message to the Church as it challenges our obsession with security, our faithlessness and our disunity.

Thank God for Augustine and his Mission. Thank God for Columba and the Celtic saints. Thank God for faithful witnesses to the Gospel throughout the ages. May God bless us and encourage us as we seek to be Ambassadors for Christ, his agents of peace and reconciliation.