This: So, Why is Evangelicalism Not Declining? Because Non-Attenders Are Taking On the Label. “Evangelicalism” is holding steady in numbers (unlike most faith groups in the US) because more and more non-churchgoers adopt the label.
Note: There are many congregations on non-white people who are, theologically speaking, Evangelicals. But neither the media nor (I think) they themselves are prone to using the label. If trends continue, “Evangelical” may come to mean “white people who don’t go to church but want to identify as Christians.”
(From Ryan Burge’s always interesting Religion in Public blog.)