The word “apocalypse” in its original usage simply means unveiling. The book of Revelation in the Christian bible means an unveiling of things to come. The apocalypse has traditionally been associated with some violent ending to the world as we know it.
In Girardian mimetic theory, the “apocalypse” is not something caused by God but caused by human beings through their own violence. The escalation of mimetic rivalries and the decreased power of the scapegoat mechanism in modernity (because it has been drained of its power through the revelation of the crucifixion) means that there are no “braking mechanisms” on violence. In this environment, an apocalyptic type of violence that wipes out all of humanity is possible. In short, an apocalypse is a form of mimetic violence that is escalated to the extreme: the scenario captured in Girard’s last book, Battling to the End.