Revivalism is similar to evangelism, except that evangelism focuses on nonbelievers while revivals focus on Christians whose faith needs renewing.
The New Testament shows Christianity as a new faith, so it says more about evangelism than revivals. Acts 3:19 refers to “times of refreshing” that come from the Lord, and many preachers have looked upon revivals as “times of refreshing” to revitalizing faith.
The Old Testament had its own revivals, as worship and morals were reformed under kings like Hezekiah and Josiah. After the return from exile in Babylon, the scribe Ezra led the Jews in a rededication to their faith.