On 17th August, 1308, the Abbess Chiara of Montefalco, in Umbria, died. In spite of the heat, her body did not decompose and the community, on seeing this, decided that it was a sign of sanctity. They resolved, therefore, to embalm her. First they disembowelled her and put the entrails in a box, which they then buried in the oratory. Then they took out her heart and placed it in another box. The day after this procedure had taken place, Sister Francesca of Foligno dissected the heart and, according to reports, found inside it a cross. The day after that, Sister Francesca got her knife to work again and discovered, or so it was claimed, tiny versions of the crown of thorns, the rod, the sponge, the whip and the nails of Christ's Passion. Miracles followed and the sisters and the townspeople set in train the process to have the abbess canonised.

Only a short distance away from Montefalco lies the town of Assisi, and there, only a few decades earlier, St Francis had also died. You will be very aware of some of the elements of his story - the lyrical beauty of the Canticle of the Sun; the renunciation of wealth; simplicity of life. What is perhaps less well known was his propensity for taking all his clothes off and leaping into rose bushes.

The curious thing about medieval understandings of sanctity is how it was so often associated with extremism - whether the extremism was of fanciful autopsies or of jumping naked into rose bushes. The greater the extremes, the more holy was the person thought to be. The thirteenth century saw this come to literary fruition in the publication of the Golden Legend - stories of the saints drawn from every age but stories which were marked by reverence for the extreme. Like St Macarius, for example, who was apparently so mortified when he killed a flea that he went naked into the desert for six months - and returned covered in bites and scabs.

This taste for the extreme and its association with sanctity strikes our age as odd, a kind of freak show of neuroses and psychoses. Much of the extremity seemed to be based upon a pathological self-hatred, a terror of the body and of all things sensual. Theologically, it implied a God so disgusted with His own creation that He demanded, bizarrely, that we share His disgust. So hair shirts and self-flagellation were the order of the day. I suspect that we, in the twenty-first century, would not be likely to regard Macarius as a saint, and the lack of decomposition in the body of an abbess would not be seen, in our age, as a sign of sanctity. Priding ourselves on our own post-Freudian sophistication, we smile with a patronising benevolence on our medieval forebears.

But I venture to suggest that extremism in our faith never really goes away. It is an inherent part of our human nature and extremism merely takes new forms. In our generation extremism takes the form of wanting to exclude, of wanting to claim that we alone are the true Christians. Our extremism shouts loudly that everyone else is failing to live up to the Gospel - and that we alone are holy, pure, undefiled. We don't leap into the rose bushes ourselves, we throw others in.

In the Anglican Communion the spirit of exclusion is having a field day - crashing and rampaging around, and causing deep hurt in the process. But what is true in the Anglican Communion, is true in dioceses and true within and between parishes - and true within our own souls. We have to look very close to home if we are to try to discern what the spiritual sources are for this kind of behaviour. The root cause is a profound lack of human generosity, based theologically upon a withered, vengeful view of God.

Let me pull the focus in even more closely, to our own country, because I sense that meanness of soul, meanness of spirit, is now our besetting national sin. If you want evidence for this, let me give you some. The way we treat the mentally ill in our country is appalling - if cuts are to be made in the NHS, who is the first to be thrown out? Answer: the mentally ill and the frail elderly. The way we treat our civic spaces is increasingly mean - tatty town centres, strewn with litter. The way we treat new housing - mean, mean, mean - pile in as many as you can in as small a space as possible, and then, heaven help us, talk of any tiny gesture towards the community as 'planning gain'. We are becoming a mean society; there is no sense of civic generosity, no sense of communal generosity.

Well, move your attention from that meanness of spirit to this day's event - to the huge generosity of the clergy and people of this Cathedral - and then move your attention further to Alban: no hair shirt; no flagellation; no self disgust. Instead we find the simple, honourable, utter self-giving generosity of a man who, having glimpsed the generosity of God, gave his life for the faith. If that isn't good news, if that isn't countercultural, if that isn't a challenge to our Church and our society, I do not know what is.

At this Eucharist we receive the overwhelming generosity of God; in the gifts of creation we see and receive the prodigal, overflowing generosity of our Creator; in the sacrifice of Christ on the cross we see the generosity of God's very being revealed to us. On this, St Alban's Festival, let us resolve to work for a Church and a nation which is generous - generous with the holy, merciful and abundant generosity of God.

© Christopher William Herbert, 2006