In the United States, evangelicalism is a movement among Protestant Christians who believe in the necessity of being born again, emphasize the importance of evangelism, and affirm traditional Protestant teachings on the authority as well as the historicity of the Bible. Comprising nearly a quarter of the U.S. population, evangelicals are a diverse group drawn from a variety of denominational backgrounds, including Baptist, Mennonite, Methodist, Pentecostal, Plymouth Brethren, Quaker, Reformed and nondenominational churches.

Evangelicalism, also called evangelical Christianity or evangelical Protestantism, is a worldwide interdenominational movement within Protestant Christianity that emphasizes the centrality of sharing the "good news" of Christianity, being "born again" in which an individual experiences personal conversion, as authoritatively guided by the Bible, God's revelation to humanity. The word evangelical comes from the Greek word for 'good news'.