It's a great exploration of the Christian-Muslim relationship, and particularly the doctrine of the Trinity. If you haven't read it, do it. Here is a snippet:
And Christians believe that this life enters into ours in a limited degree. When God takes away our evildoing and our guilt, when he forgives us and sets us free, he breathes new life into us, as he breathed life into Adam at the first. That breathing into us we call the 'Spirit'. As we become mature in our new life, we become more and more like the expression of divine life, the Word whom we encounter in Jesus. Because Jesus prayed to the source of his life as 'Father', we call the eternal expression of God's life the 'Son'. And so too we pray to the source of divine life in the way that Jesus taught us, and we say 'Father' to this divine reality.
But in no way does the true Christian say that the life and action of God could be divided into separate parts, as if it were a material thing. In no way does the true Christian say that there is more than one God or that God needs some other in order to act or that God promotes some other being to share his glory. There is one divine action, one divine will; yet (like the fingers of the hand) there are three ways in which that life is real, and it is only in those three ways that the divine life is real – as source and expression and sharing. It is because of those three ways in which divine life exists that Christians speak as they do about what it means to grow in holiness.
And the Christian also says something which may again be a source of disagreement. God is a loving God, as we all agree; but, says the Christian, God does not love simply because he decides to love. He is always, eternally, loving. His very nature, his definition is love. And the interaction and relation between the three ways in which God lives, the source and the expression and the sharing, is eternally the way God exists. The three centres of divine action, which we call Father, Son and Spirit, pour out the divine life to each other for all eternity, a sort of perfect circle of giving and receiving. And the only word we can use for that relationship of pouring out and giving is love. So as we grow in holiness, we become closer and closer in our actions and thoughts to the complete self-giving that always exists perfectly in God's life. Towards this fullness we are all called to travel and grow.
One thing that I'm trying discern from the lecture is Williams comment that 'God' is the name of a kind of life which is lived in three ways. He further describes the three persons of the trinity as 'three centres of divine action'. How does this description of the Father, Son and Holy Spirit sit with you? Let me know your thoughts.