They are small, godly and growing at an incredible rate.
They are "fresh expressions" of church and until now, they have had little attention beyond those directly involved.
Yet these fxC churches are springing up across the country in pubs, skate parks, schools, offices.
They are flourishing in almost any space where to God is to be found - and in many spaces where it had been thought He could not be.
In ten years, they have quadrupled in number.
More than 1,100 of these new fxC churches now to be found working with "the disturbing but renewing Spirit of God", according to new research by the Church Army, a mission arm of the Church of England.
Leading these churches are nearly 600 "untrained and unauthorised" lay men and women who were "unknown" before the Church Army did its research.
And unlike most of the larger, evangelical megachurches where nearly all the leaders are men, dozens of gifted Christian women are emerging as capable leaders of fxC churches.
The Church Army says the established Church must not "despise" these new congregations, which attract twice the number of under-16s as mainstream churches.
The Church Army says: "Now may be the day of small things: a diverse set of small, sometimes frail, mainly young churches that lay a claim to being among our best hopes for the future. They are not the whole answer, but they are one sign of reform as well as renewal within the Church of England."
A fresh expression of church is a new gathering or network that engages mainly with people who have never been to church. The emphasis is on starting something new that is appropriate to its context, rather than cloning something that works elsewhere.
Across all 42 dioceses of the Church of England, there are now thought to be more than 3,000 fxC churches.
Across those surveyed in 21 dioceses, more than 50,600 people belong to 1,109 new fxC congregations. Half of these young churches are being led by women.
The report says the most common types of fxC churches are Messy Church, café church, child-focused church and church plants. There are 20 types in total, including "cluster" churches, new monastic communities, "cell" churches, churches for the under-5s, youth churches and even fxC churches for "older people".
The report says most fxC churches rarely hold communion status and often have "no legal status" at all within the Church of England.
The Church Army's research unit spent four years invetigating the fxC phenomenon.
One significant finding is that just 10 per cent of attenders transferred from another local church, meaning these are new church members and not "stolen" from another church.
Members are much younger than normal, with an average age of 25-34 against the average age of 65 for parish church attenders. And fxC are doing particularly well on some of England's poorer housing estates.
George Lings, Church Army director of research, who unveiled the findings at the Wilson Carlile Centre in Sheffield, said: "FxC is essentially a journey outwards, aimed at building relationships and helping people who are not currently church attenders to discover faith. Simply put, an fxC reimagines what it is to be a community around Christ, and how to stay faithful to traditional church, while at the same time, being more creative.
"Our hope is that this report may prove to be the best guide for dioceses, and the Church of England as a whole, about both the characteristics and performance of its younger churches for the next decade."
This video shows some of the early findings of the four-year Church Army research project into fxC.