In his Christmas morning sermon the Archbishop of Canterbury, Dr Rowan Williams, warned that if people threaten the planet there will be repercussions. Here is the sermon in full:
Eleven days ago, the Church celebrated the memory of the sixteenth century Spanish saint, John of the Cross, Juan de Yepes - probably the greatest Christian mystical writer of the last thousand years.
A man who worked not only for the reform and simplification of the monastic life of his time, but also for the purification of the inner life of Christians from fantasy, self-indulgence and easy answers.
Those who've heard of him will most likely associate him with the phrase that he introduced into Christian thinking about the hard times in discipleship - 'the dark night of the soul'.
He is a ruthless analyst of the ways in which we prevent ourselves from opening up to the true joy that God wants to give us, by settling for something less than the real thing, and confusing the truth and grace of God with whatever makes us feel good or comfortable.
'Disturbing and difficult'
He is a disturbing and difficult writer; not, you'd imagine, a man to go to for Christmas good cheer.
But it was St John who left us, in some of his poems, one of the most breathtakingly imaginative visions ever of the nature of Christmas joy, and who, in doing this, put his own analyses of the struggles and doubts of the life of prayer and witness firmly into an eternal context.
He is recognised as one of the greatest poets in the Spanish language; and part of his genius is to use the rhythms and conventions of popular romantic poetry and folksong to convey the biblical story of the love affair between God and creation.
One of his sequences of poetry is usually called simply the Romances.
It's a series of 75 short, mostly four-line, verses, written in the simplest possible style and telling the story of the world from the beginning to the first Christmas - but very daringly telling this story from God's point of view.
It begins like a romantic ballad.
'Once upon a time', God was living eternally in heaven, God the Father, the Son and the Holy Spirit, with perfect love flowing uninterrupted between them.
And out of the sheer overflowing energy of his love, God the Father decides that he will create a 'Bride' for his Son.
The imagery is powerful and direct: there will be someone created who will be able, says God the Father, to 'sit down and eat bread with us at one table, the same bread that I eat.
And so the world is made as a home for the Bride.
Who is this Bride? It is the whole world of beings who are capable of love and understanding, the angels and the human race.
In the rich diversity of the world, the heavens and the earth together, God makes an environment in which love and intelligence may grow, until they are capable of receiving the full impact of God's presence.
And so the world waits for the moment when God can at last descend and - in a beautiful turning upside-down of the earlier image - can sit at the same table and share the same bread as created beings.
As the ages pass on Earth, the longing grows and intensifies for this moment to arrive; and at last God the Father tells the Son that it is time for him to meet his Bride face to face on earth, so that, as he looks at her directly, she may reflect his own likeness.
When God has become human, then humanity will recognise in his face, in Jesus's face, its own true nature and destiny.
And the angels sing at the wedding in Bethlehem, the marriage of heaven and earth, where, in the haunting final stanza of the great poetic sequence, humanity senses the joy of God himself, and the only one in the scene who is weeping is the child, the child who is God in the flesh:
'The tears of man in God, the gladness in man, the sorrow and the joy that used to be such strangers to each other.'
Well, that is how John of the Cross sets out the story of creation and redemption, the story told from God's point of view.
And there are two things in this that are worth our thoughts and our prayers today.
The first is one of the strangest features of John's poems.
The coming of Christ is not first and foremost a response to human crisis; there is remarkably little about sin in these verses.
We know from elsewhere that John believed what all Christians believe about sin and forgiveness; and even in these poems there is reference to God's will to save us from destruction.
But the vision takes us further back into God's purpose.
The whole point of creation is that there should be persons, made up of spirit and body, in God's image and likeness, to use the language of Genesis and of the New Testament, who are capable of intimacy with God - not so that God can gain something but so that these created beings may live in joy.
And God's way of making sure that this joy is fully available is to join humanity on earth so that human beings may recognise what they are and what they are for.
The sinfulness, the appalling tragedy of human history has set us at what from our point of view seems an unimaginable distance from God; yet God, we might say, takes it in his stride.
It means that when he appears on earth he takes to himself all the terrible consequences of where we have gone wrong - 'the tears of man in God' - yet it is only a shadow on the great picture, which is unchanged.
We are right to think about the seriousness of sin, in other words; but we see it properly and in perspective only when we have our eyes firmly on the greatness and unchanging purpose of God's eternal plan for the marriage of heaven and earth.
It is a perspective that is necessary when our own sins or those of a failing and suffering world fill the horizon for us, so that we can hardly believe the situation can be transformed.
For if God's purpose is what it is, and if God has the power and freedom to enter our world and meet us face to face, there is nothing that can destroy that initial divine vision of what the world is for and what we human beings are for.
'Celebration of mystery'
Nothing changes, however far we fall; if we decide to settle down with our failures and give way to cynicism and despair, that is indeed dreadful - but God remains the same God who has decided that the world should exist so that it may enter into his joy.
At Christmas, when this mystery is celebrated, we should above all renew our sheer confidence in God.
In today's Bethlehem, still ravaged by fear and violence, we can still meet the God who has made human tears his own and still works ceaselessly for his purpose of peace and rejoicing, through the witness of brave and loving people on both sides of the dividing wall.
But the second point growing out of this is of immense practical importance.
The world around us is created as a framework within which we may learn the first beginnings of growing up towards what God wants for us.
It is the way it is so that we can be directed towards God. And so this is how we must see the world.
Yes, it exists in one sense for humanity's sake; but it exists in its own independence and beauty for humanity's sake - not as a warehouse of resources to serve humanity's selfishness.
To grasp that God has made the material world, 'composed', says John of the Cross, 'of infinite differences', so that human beings can see his glory is to accept that the diversity and mysteriousness of the world around is something precious in itself.
To reduce this diversity and to try and empty out the mysteriousness is to fail to allow God to speak through the things of creation as he means to.
'My overwhelming reaction is one of amazement. Amazement not only at the extravaganza of details that we have seen; amazement, too, at the very fact that there are any such details to be had at all, on any planet.
'Extravaganza of details'
The universe could so easily have remained lifeless and simple. Not only is life on this planet amazing, and deeply satisfying, to all whose senses have not become dulled by familiarity: the very fact that we have evolved the brain power to understand our evolutionary genesis redoubles the amazement and compounds the satisfaction.'
The temptation to quote Richard Dawkins from the pulpit is irresistible; in this amazement and awe, if not in much else, he echoes the 16th century mystic.
So to think of our world as a divine 'prompt' to our delight and reverence, so that its variety, the 'extravaganza of details', is a precious thing, is to begin to be committed to that reverent guardianship of this richness that is more and more clearly required of us as we grow in awareness of how fragile all this is, how fragile is the balance of species and environments in the world and how easily our greed distorts it.
When we threaten the balance of things, we don't just put our material survival at risk; more profoundly, we put our spiritual sensitivity at risk, the possibility of being opened up to endless wonder by the world around us.
And it hardly needs adding that this becomes still more significant when we apply John of the Cross's vision to our human relations.
Every person and every diverse sort of person exists for a unique joy, the joy of being who they are in relation to God, a joy which each person will experience differently.
And when I encounter another, I encounter one who is called to such a unique joy; my relation with them is part of God's purpose in bringing that joy to perfection - in me and in the other.
This doesn't rule out the tension and conflict that are unavoidable in human affairs - sometimes we challenge each other precisely so that we can break through what it is in each other that gets in the way of God's joy, so that we can set each other free for this joy.
This, surely, is where peace on earth, the peace the angels promise to the shepherds, begins, here and nowhere else, here where we understand what human beings are for and what they can do for each other.
'Glory to God'
The delighted reverence and amazement we should have towards the things of creation is intensified many times where human beings are concerned.
And if peace is to be more than a pause in open conflict, it must be grounded in this passionate amazed reverence for others.
The birth of Jesus, in which that power which holds the universe together in coherence takes shape in history as a single human body and soul, is an event of cosmic importance.
It announces that creation as a whole has found its purpose and meaning, and that the flowing together of all things for the joyful transfiguration of our humanity is at last made visible on earth.
'So God henceforth will be human, and human beings caught up in God. He will walk around in their company, eat with them and drink with them.
'He will stay with them always, the same for ever alongside them, until this world is wrapped up and done with'.
Glory to God in the highest, and peace on earth to those who are God's friends.