Filing evangelicalism as a denomination is a category error, and it is worth stating why rather than quietly committing it.
A denomination has a boundary. It can say who its members are, ordain and remove its clergy, own property, adopt a confession and discipline those who depart from it. Evangelicalism can do none of these things. It has no register, no synod, no confession that binds and nobody with authority to exclude. An evangelical Baptist, an evangelical Anglican and an evangelical Presbyterian belong to three different churches with incompatible views of baptism and church government, and are evangelicals in the same sense.
What holds it together is a set of emphases, described by the historian David Bebbington in four terms that are now standard: conversionism, that lives must be changed; biblicism, a high view of scripture's authority; crucicentrism, a focus on the cross; and activism, the expression of all this in preaching, mission and social effort. The definition has been criticised for being too broad to exclude much and for describing British evangelicalism better than the global movement, but nothing has displaced it.
The word is now contested in a way that has little to do with theology. In the United States it functions in survey research and journalism as a demographic and political label, applied by pollsters on the basis of self-identification, and the population it picks out is not the same as the population that meets Bebbington's description. Scholars have responded in different directions: Donald Dayton called for a moratorium on the term; D. G. Hart argued that evangelicalism as a religious identity does not exist and should be abandoned; others hold that a movement of this size cannot be defined out of existence because its American branch has been captured by a political usage.
The World Evangelical Alliance claimed 600 million adherents in 2025. The figure comes from the movement's own body, rests on a definition the movement itself disputes, and should be read as an order of magnitude rather than a count.