The fourth century was a time of heady excitement for Christianity in the Roman Empire. All because of a battle fought and won by the Emperor Constantine who saw the sign of the cross in the sky the night before his victory, Christianity went overnight from being a persecuted minority to being the official, state-sanctioned and virtually compulsory religion. Theology became the hot topic of conversation in the corridors of power - can you imagine rival politicians arguing about Jesus? And the sort-of Christian Emperor Constantine had to call a conference at Nicaea in modern-day Turkey to sort out once and for all: was Jesus divine? And Constantine got the result he wanted - by stacking the conference with the bishops he approved of and personally vetting the resulting consensus that formed the backbone of today’s Nicene Creed.

The Creeds of course don’t explain anything, in the solemn formulas passed down through the centuries ladn with the metaphysical terminology of the ancient Greeks they assure us of the seeming impossibility that Jesus Christ shares the fullness of divinity with God and the fullness of humanity with us. But the Creeds do set some boundaries, informing us that if we believe that salvation comes through Jesus Christ, we can’t then say that Jesus is just a man - a good man, of course, but just a man and so in need of salvation himself and unable to help us - or alternatively that Jesus is just God in disguise and so does not really share in the vulnerability of our mortality. The creed of Nicaea didn’t really settle the debate wich raged on in the churches of Asia Minor for another century and a half before the uneasy truce of the Council of Chalcedon but the question is as relevant today as it was in the fourth century - who, actually, is Jesus?

Last week, you remember Peter gets it sort of wrong - wanting to follow Jesus out onto the surface of the lake he chickens out and sinks in fear and confusion. And I suggested that Jesus, far from admonishing Peter, speaks tenderly to him and praises him as one who does in fact have a little faith. This week Peter apparently gets it right - but straight away Jesus tells him to shut up and three verses later - next week’s reading - will tell Peter he is speaking the words of Satan.

So - ‘who do people say that I am?’, Jesus asks his disciples, and they hazard several guesses - the general consensus being that Jesus is a prophet. Perhaps Jesus is even the greatest prophet, Elijah, returned again as Jews believed would happen before the last day. But then it’s a light-bulb moment for Peter, who all of a sudden gets it. ‘You are the Messiah’, he says - and Matthew gets this part of Peter’s answer from the earliest gospel, from Mark’s version of the same story. Now the word messiah - in Hebrew, mashiach - means ‘anointed’ and for hundreds of years Israel had been expecting a political leader anointed by God, a successor to the great King David. In the time after the return from exile 300 or so years before Jesus the yearning for a messiah had begun to take on religious overtones as well. But the messiah who was and is even today the expected salvation of Israel is not the suffering servant but a triumphal leader. And as we read on further in Matthew’s Gospel we will realise that yes, Peter is right because Jesus is the salvation of his people; but he’s also wrong, because what Peter thinks he means by that and who Jesus understands himself turn out to be are entirely different. This is why Jesus tells the disciples to be silent.

In Mark’s Gospel that’s pretty much where the story ends but in Matthew there is another point to the story. Because now - a generation further along than the first Gospel - the issue of who Jesus is - is connected to the question of who and what the Church is. And so in Matthew’s Gospel, Peter says ‘you are the Messiah’, and then he adds, ‘the Son of the living God’.

See, we are starting to get into the territory of the Creeds. We are also getting into the territory of slippery language, and we need to tread carefully. Jesus as messiah is a leader, for sure, a leader anointed by God and enacting God’s purposes for Israel. But - Jesus as the Son of God? What does this even mean when Peter says it? For a start, not quite the same thing as when we say it, with the echo of the creeds of the ancient Church ringing in our ears. The religion of Israel was not metaphysical or speculative, and it was fiercely monotheistic. The could be no multiplicity of gods, no divine dynasty. But Israel itself could be and in the Hebrew Bible is referred to as the son of God, King David and his descendants are called sons of God - because in Hebrew to be the ‘son of’ means to derive from, and to emulate. It’s perhaps in this sense that Peter confesses that Jesus’ life is so grounded in and in loving communion with the one he calls his Father that Jesus reveals who God is. It’s a massive claim and one that finds its fullest meaning in the light of resurrection. And so the phrase ‘Son of God’ in Matthew’s Gospel and thereafter takes on the deeper meaning that in Jesus we see ‘God with us’.

As a title applied to Jesus in the first century, even near the end of the century when Matthew is writing his Gospel, this claim stretches the limits of Jewish religious sensibility - and it is also politically shocking for the reason that the other person who is called the Son of God in the first century is the Roman Emperor. By confessing Jesus as the Son of God, Peter is not only saying that in Jesus we see God with us - he is also claiming that it is Jesus who is the Son of God - not the Emperor. The real power in this world is not the military or the economic power of Rome but the relational power, the power of compassion and radical forgiveness that comes from God and we see revealed in Jesus.

And the direct implication of how Matthew writes it - and the implication of how the creeds of the fourth and fifth centuries wrestle with the intuition that in Jesus we see God sharing our humanity, and our humanity being opened to God’s grace - the direct implication is that it also poses - and answers - the question, ‘who then are we?’ ‘You are the rock’, Jesus tells Peter, ‘and on this rock I will build my church’. Well, a sentence like this probably couldn’t have been written until there was actually a church, which is why we see it in Matthew’s gospel and not Mark’s earlier version. Also, Peter is anything but rock-solid so there is a bit of humour about this pronouncement, but the rock in question on which the Church of God will be founded is not so much Peter’s kind of flaky and not very courageous person but his confession of faith. You see Jesus, as the Word of God made flesh who if we follow the Creeds is one with the Father, of one substance with God but at the same time also one with us - very God with very God and at the same time sharing our vulnerable human nature, prone to aches and pains and tiredness and self-doubt and love and anger just like us - as the Orthodox Church in particular insists, Jesus is not just the Son of God to impress us but also to complete us. In Jesus, God shares our humanity and so makes our humanity capable of being opened to God. That is why the Orthodox speak of the Incarnation as the perfection of creation.

And moving forward in history it also means that the perfection of creation - is us. We as men and women and children who know ourselves to be the body of Christ, are the new humanity founded on the rock of Peter’s confession. Jesus in this passage gives the basic instructions for being the Church, assuring us we are to be nothing less than the bulwark against Satan and the portal of heaven. Don’t let it go to your head, of course, but what is meant here, what Matthew the writer of the Gospel is telling his community and us is that who we are is forever changed if we take seriously the truth that Peter stumbles on - in Jesus we experience God sharing the intimate centre of our lives and that makes our lives a sacrament that reveals God. No wonder the good Emperor Constantine refused to accept baptism until he was on his deathbed! Because if we dare to repeat the confession of Peter, and if we claim to actually believe it, then we are making a claim not just about Jesus’ substance but our own as well. To be Christian is to be an icon made out of flesh and blood that reveals God with us.

Of course, we are not very good at yet. Because, like Peter - and also like Jesus of Nazareth actually - we are fully human and so we are also prone to error and distraction and self-centred foolishness. But to be Christian is to commit ourselves to living the way of radical forgiveness and self-giving love. To have at the centre of our vision of reality the one whom we in all seriousness claim to be God with us raises the stakes! It challenges us to live in a way that is transformational - which means a way that gives life to others, and that is oriented toward the future in hope. Good thing we are in it together.