Tim Callahan is a regular contributor to Skeptic and a long-time student of biblical and end-times prophecy. His book, Bible Prophecy: Failure or Fulfillment? was recently published by Millenium Press. He is presently working on a book about the millenium and end-times doomsayers. He has also researched the environmental movement, and his article "Environmentalists Cause Malaria! (and other myths of the 'Wise Use' movement)" appeared in The Humanist.