To say that evangelicals have neglected ecclesiology is not to say that they have neglected the church altogether. What they have neglected, rather, is a rich theological account of the church. An honest evaluation of evangelicalism must conclude that evangelicals have oftentimes conceded ecclesiology to sociology, history, and, in the worst instances, to entrepreneurship. Evangelicalism to a great degree does not have a richly Trinitarian, Christological, and pneumatological understanding of the church (though there are ever-increasing attempts to address this deficiency).
There are at the very least two reasons for this lack of rich theological description. First, evangelicalism is most often understood as a sociological and historical movement. This view of evangelicalism in turn translates into a sociological view of the church rather than a theological one. Second, practitioners more interested in pragmatic and numerical success than theological reflection are often the ones who shape evangelical ecclesiology. In the words of Barth, they are often more impressed with extensive rather than intensive growth, numerical rather than spiritual increase (though, as Barth himself noted, these need not be mutually exclusive). Nevertheless, to treat the church as a society among societies, as an organization among organizations, as a sociological entity marked by visible success accounted for by secular methods, is to take flight into the visible church and sacrifice its theological identity. What is required is a much more robust theological doctrine of the church.
~Kimlyn Bender, “The Church in Karl Barth and Evangelicalism: Conversations across the Aisle.” in Karl Barth and American Evangelicalism, 192-193.