Harold is an elderly fellow with a soft voice and gentle demeanor. That is, until you give him grief about his belief that the Rapture is to take place on May 21, 2011, and that the world will end on October 21 the same year. Give him any sass or question his sanity, and the gloves come off.
Even most Christians think this guy is a clown. Albeit, a clown who thinks he's genuinely doing the right thing, but a clown, nevertheless.
A challenge for Mr. Camping: if you're so sure that the Rapture is set to take place on May 21 next year, I want you to send all of your money to my Paypal account on May 20th. If not that, then on May 22, 2011, I want you to give all of the money back to everyone you ever duped into believing your crap.