(CBS4) – You may have seen them around town: billboards saying this Saturday is Judgment Day.

The man who started that message is from Boulder. Harold Camping is the head of Family Radio, a Christian ministry that predicts May 21 as the day believers will be saved and the rest will suffer. They say the Bible proves it and that God has revealed the date now beause believers have the technology to spread the message.

“Every time he’s brought judgment he’s warned the belivers first. So they in turn can warn the world,” Gunther von Harringa, Family Radio spokesman, told CBS4 on Tuesday. “Without a shadow of a doubt, it is going to happen.”

Dr. Miguel De La Torre, a professor at the Illif School of Theology, also cites scripture, but uses it as a basis for his explanation of why judgment day won’t happen this weekend.

“I can assure you, the world is not going to end on Saturday,” he said. “You can manipulate biblical text, and manipulate numbers with the world ending any day you want.”

Family Radio first predicted the end would happen in 1994.