There are 4,000 people in Centenary Square. Most of them are young. Many of them are Black, some are Asian and some are White. Many are carrying home-made placards. There are waves of chanting: No Justice, No Peace; Enough is Enough; Say their Names; I can’t breathe; Black Lives Matter.

There is a lull in the chanting. It lasts longer than other silences and I notice that the people in front of me are ‘taking the knee’, lowering themselves to the ground in a symbolic gesture of reverence and humility.My son Joel and I and the people standing around us join them. Soon the whole square is kneeling and quiet. Placards are lowered. There is a pause followed by spontaneous, sustained applause.

I don’t know why 4,000 people knelt or what they were thinking. I can only guess. Some of us, I am sure, were honouring lost friends. Black people who have died in custody, in prison, in bungled arrests and on our streets. Some of us were honouring Black lives diminished by racism; people who have suffered injustices perpetrated by our systems of housing, education, and social care. Some of us were acknowledging our role, the times we have been silent, the times we have exploited our privilege unthinkingly, the times we have not cared enough to do or say anything. Perhaps some of the White Christians were thinking about our particular history; from the slaves branded with the initials of an Anglican mission organisation, to the lack of hospitality shown to the Windrush Generation and the unconscious bias still faced by Black people who seek to be a full part of our institution.

As the clapping faded, people stood again but we were changed. Changed by our corporate act of repentance, remembrance, and reconciliation. It reminded me of the Climate Strikes and once again we were being led by young people, people the age of my children, who seem to be the prophets for our times.

I feel ashamed that we have left the world such a mess and our young people are now being forced to take a lead, to tell truths we would rather hide and ask questions we don’t want to answer. They have not yet got so tied up with the systems that they are afraid to challenge. They have not invested in the structures to such an extent that the prefer the status quo to anything new.

Sometimes as Christians, we are not expected to ask many questions. We listen to sermons like this without being asked to interrogate what is being said. We have neat doctrines and formulas that tell us how to behave, who will get to heaven, how God is experienced and how we should worship. But at Trinity it is hard not to ask questions. I am yet to meet anyone who can give me a convincing explanation of what it means to worship this three-in-one God.

When I am asked about it, and I am a lot in interfaith conversations, I can’t and don’t want to offer a tidy doctrinal package. I can only offer the truth, that it is a metaphor, a mystery, poetry. Imagery reaching for that which can’t be described. The deepest, most beautiful things cannot be described directly. We don’t have all the answers. Our faith is not cut and dried. Our understanding of God is not complete.

And now we are learning again, our understanding of the world is not complete. We have had blinkers on and made assumptions. We have accepted bland explanations and half-truths because it is convenient to us. Our young people are now begging us to look again. They are calling us like the prophets to envision a new way of living. They are challenging us to stop living as if racism, supremacy, patriarchy, and the exploitation of the planet are inevitable.

One of my boys said this week that they could not understand why the church is not at the forefront of the movement for change. I am sure that question is being asked by many in that generation.

We need to change. As individuals and as a body. We need to ask some questions of ourselves and of those in power. We need to accept that what we have always known is not all there is. We need to welcome voices that are not often heard to explain our scriptures and share their experiences with us. We need to renew our faith and change our ideas about God, in order that God, so often depicted as a white, blue-eyed, European man stops being familiar. We need to allow our faith to be a source of questions, not a store of easy answers.

One thing that is often said of the Trinity is that is a model of community. Challenge can sound overwhelming or accusatory when we hear it alone. And today we can’t be together but we remain a community. Together we can learn to practice how to live as Jesus lived, empowered by the Holy Spirit so that all God’s children in their diversity and difference may know justice, peace and freedom in a society where no life is worth more than another and no-one is martyred for the colour of their skin.