"It is a very ancient pattern in human thought. It is rooted in ancient, even pre-biblical Middle Eastern myths of ultimate chaos and ultimate struggle between the forces of order and chaos," says cultural historian Paul S Boyer, author of When Time Shall Be No More: Prophecy Belief in Modern American Culture.

"It is deeply appealing at a psychological level because the idea of meaninglessness is deeply threatening. Human societies have always tried to create some kind of framework of meaning to give history and our own personal lives some kind of significance."

And although end of the world thinking crops up in many religions, those in the West are probably most aware of Christian eschatology. In the early days of the church it was taken as a given by many believers that the Second Coming and the end of the world were imminent.

Mainstream Christianity moved away from this type of thought, but large numbers of believers returned to it at various times.

"It isn't just the lunatic fringe, it's an integral part of all Christianity. But [in mainstream Christianity] it is put into perspective that it may happen 'one day'," says Stephen J Hunt, a sociologist of religion and author of Christian Millenarianism: From the Early Church to Waco.

"But certain groups and movements believe it is in their generation. They are saying we have got the truth and nobody else has."