Today is Trinity Sunday in the church’s calendar – part of Christians’ journey through the year, giving shape to the narrative of God’s engagement with people.

The Trinity is not merely a theological conundrum, dreamed up by weirdos for people with an interest in mathematical paradoxes, but rather relates to the whole of God and our common life in church and society. To put it simply (which, of course, begs a whole load of other questions), the mutuality of relationship between God as Father, Son and Holy Spirit depicts what has been referred to elsewhere as a network of mutual obligations that bind them together in a single, common life.

Mutuality is essential to our common life in the church. Why do we in the Church of England begin every act of worship with some form of repentance – holding up our hands and admitting publicly to hypocrisy, weakness and failure as individuals and as a community? Because we assume this relationship of obligation and compensation, and recognise that it imposes upon us responsibilities from which we cannot duck. We bring different gifts and contribute our unique limitations, too; but, together, we somehow hold together and serve the world we are in.

So far, so good. But, what does this say to a society that widely considers theological ideas to be esoteric, but of only private application to those who choose to be interested?

Without getting too complicated, I think the answer begins here. Human society in a contingent world can only thrive if the networks of mutual obligation are (a) recognised and (b) seen to transcend my individual preferences, needs and desires. The rest of the church’s year involves wrestling with the implications of this – not just for the church, but also for our public and political life nationally, and for the good of the world beyond our shores. That’s why we work through the Bible, being confronted by the difficult and discomfiting bits as well as those that reassure or comfort.

It is appropriate, then, to conclude this brief piece with an appreciation of a man who has challenged and encouraged both church and society to examine our assumptions and blind spots, to live out our common mutuality, and to live better together. The Archbishop of York, Dr John Sentamu, who retires today has inspired people to think bigger, to be encountered by the love and call of God, to take responsibility for our common political and ethical life, and to work hard for a better and more humane world. His personality, character and conviction will be missed – although I doubt it is about to disappear from our public life. We owe him a huge debt of gratitude and, as he would particularly want to affirm, give glory to God for all he has been and done in the name of Jesus in the power of the Spirit.