Christopher Columbus (1451-1506) sailed to the western hemisphere from Spain in 1492; a myth developed that this voyage proved that the earth was round (and not flat), but this had been known for many years in many cultures. The term “flat earther” (or “flat-earther”), cited in print since at least 1877, refers to someone who still believes that the earth is flat, but the term has also been used to describe a person who irrationally rejects science.
 
U.S. President Barack Obama, in March 2012, talked about his alternative energy policies and his Republican critics, saying “If some of these folks were around when Columbus set sail, they must have been founding members of the Flat Earth Society.” The media reported that Obama had called his opponents “flat earthers,” a term similar to “birther” in labeling Obama’s opponents as “crazy.”
 
   
Wikipedia: Flat Earth Society
The Flat Earth Society (also known as the International Flat Earth Society or the International Flat Earth Research Society) is an organization that seeks to further the belief that the Earth is flat instead of an oblate spheroid. The modern organization was founded by Englishman Samuel Shenton in 1956 and was later led by Charles K. Johnson, who based the organization in his home in Lancaster, California. The formal society was inactive after Johnson’s death in 2001 but was resurrected in 2004 by its new president Daniel Shenton.
 
(Oxford English Dictionary)
flat-earth adj. of or pertaining to the theory that the earth is flat.
1905 Westm. Gaz. 25 Feb. 3/2   This Flat-Earth Society.
1909 Westm. Gaz. 21 Sept. 4/1   A lifelong upholder of the flat-earth theory.
1922 A. S. Eddington Theory of Relativity 26   Those who adhered to the flat-earth theory must hold that the flat map gives the true size of Greenland.
 
flat-earther n.
1934 Punch 21 Nov. 562/1   Without being a bigoted flat-earther, he [sc. Mercator] perceived the nuisance‥of fiddling about with globes‥in order to discover the South Seas.
1963 Times 11 May 6/2   His treatment of appoggiaturas was that of a Flat Earther with spasmodic doubts.
     
Google Books
Ancient Society or, Researches in the line of human progress from savagery through barbarism to civilization
By Lewis Henry Morgan
Chicago, IL: C.H. Kerr
1877    
Pg. XXV:
It would be like geographers debating flat-earthers or evolutionary geneticists debating Lamarckians.
 
The Examiner (Washington, DC)
Obama likens GOP energy critics to Flat Earthers
by Hayley Peterson Examiner Staff Writer
posted March 15, 2012 at 8:01pm
LARGO, Md.—President Obama fired back at the Republican presidential field Thursday, likening their collective criticisms about his alternative-energy policies to those who once allowed their fears of falling off the Earth prevent them from exploring new opportunities.
 
“If some of these folks were around when Columbus set sail, they must have been founding members of the ‘Flat Earth Society,’” the president told an adoring crowd in Prince George’s County. “They would not believe that the world was round.
 
“We’ve heard these folks in the past,” Obama added. “‘Television won’t last. It’s a flash in the pan’ ... ‘The horse is here to stay but the automobile is only a fad.’”
   
Human Events
The Flat Earth presidency
Obama will hold his course until we all drop dead at the oars.
by John Hayward
03/15/2012
(...)
Columbus didn’t have the entire taxpaying population of Spain chained to the oars, forced to row his ships into an endless dead calm.  And it’s Obama and his cronies whose minds are held captive to primitive environmentalist superstitions.  Notice this desperate man doesn’t have a single word to say in his defense, other than hurling insults.  He couldn’t come up with an honest, logical response to the people he derides as “flat earthers” if you put him in a room full of teleprompters.
 
Real Clear Politics
Posted on March 15, 2012
Carney: Calling GOP “Flat-Earthers” Was A “Policy Message”
Jay Carney, White House: “It seems even talking about alternative energy sources is funny and I think calling them flat-earthers is appropriate.”
Mark Knoller, CBS News: “Isn’t that a campaign message?”
Carney: “No! It’s a policy message. We believe we have to do this for the sake of America’s economic future. It is simply not an option to say that we can keep drilling with two-percent of the known oil reserves in the world when we consume 20-percent of the world’s oil. I was a mediocre math student, but that doesn’t seem to work out.”