The Evangelical Alliance's ethnically diverse church group, the One People Commission, is concerned that whilst Pentecostal and other evangelical churches in the UK pride themselves on church growth, they could be left with a much smaller next generation.
It thinks there are huge cultural differences between the first generation of migrants to the UK who built the churches and the second generation - their children who were born in the UK.
The group is calling on leaders of these churches to make changes to makes sure they keep young people interested.
Revd Yemi Adedeji, a director of the One People Commission said: "We still need to keep the faith, still keep the authenticity of what we do together but at the same time it might require, a change in the ways that things are being done.
"From my own personal perspective, when they went to university my children began to think differently about what a church for their generation should look like. It was a total paradigm shift! They think differently about what a church for their generation should look like. Now if that has happened to me personally and to many of my colleague leaders and pastors then we must wake up and embrace the challenge. If we keep quiet and we don't do anything we could lose quite a bit of the next generation. If we do nothing, we might as well wipe out the next generation's continuation of our faith."
Revd Adedeji made the comments as he launched a survey for 18-to-35 year-old evangelical Christians to reveal the issues that they are facing in evangelical churches and the changes they would like to see.
To take part in the survey head to www.eauk.org/millenialchristians.
You have until Sunday 16 November 2014.
Here Revd Yemi Adedeji speaking to Des Busteed on Premier's News Hour: