There's a new report out today on religion in British public life and for Christians, the facts it lays out about declining religious practice make uncomfortable reading. But facts they are – and Christian faith is not about evading harsh realities. Quite the opposite.

The statistics show that 'Christendom' is over. I am one of the last generation brought up within it. In the Scottish village where I grew up in the 1970s and 80s, "Church of Scotland" is what nearly everyone wrote on their admission form at hospital, whether or not they had been inside a church since their (infant) baptism. Those days are gone now, and there is no point in hankering after them. As Christians, we must accept that God is doing something new.

For, as the report recognises, there are signs of growth within some parts of the Church – and other research highlights church planting and immigration as key drivers of renewal. I have been fortunate to spend 17 years working in East London churches where Christendom is long over, but renewal is real and visible. The Centre for Theology and Community (CTC) is about to publish some exciting new research into church planting and church growth in the East End. It shows, among other things, that growth is happening in many different theological and liturgical traditions, and that acting with others for the common good is a friend to such growth, not a rival for our energy as Christians.

The link between social action and church growth is important, for the report tells the story of a Church which still makes a disproportionate contribution to the common good through works of mercy and action for social justice. It urges funders not to discriminate against faith groups when they are the best providers of a public good, and are willing to do it without pressuring users to convert. (Theos and CTC have just produced a timely guide for local churches which will help them navigate these issues.)

If Christendom is over, it is counter-productive for Christians to cling on to its trappings. The report makes a number of recommendations on education. We affirm the role of religion and belief in the formation of young people, but urge an end to the (much-ignored) anachronism of compulsory collective worship in non-religious State schools. We also call on faith schools to reduce selection by religion where it is possible to do this without diluting their distinctive ethos.

The reality must be faced: nominal Christianity is in decline, and this may be no bad thing. For the report also highlights the role of faith in challenging the status quo. It has played that role in British public life historically, often through characters at odds with the establishment such as the Wesley brothers, Catherine and William Booth and the Clapham Sect. In our own time, it is playing that role with a new intensity – through the work of churches in Citizens UK, fighting for a Living Wage, a cap on payday lending, and hospitality to refugees. We may have fewer nominal adherents, but there is plenty of evidence the Spirit is at work forming new disciples – those who seek the welfare of the earthly city, even as they best witness to their eternal hope.

Canon Dr Angus Ritchie is executive director of the Centre for Theology and Community.