What is the X in X-mas?
1650s, "act of reviving;" 1660s, "the bringing of an old play back to the stage," from revive + -al (2). First in sense "general religious awakening in a community" by Cotton Mather, 1702; revivalist is first attested 1812.
In Christianity, an energetic meeting intended to “revive” religious faith. Common among fundamentalists, these meetings are characterized by impassioned preaching and singing.