Just 66% of millennials firmly believe that the earth is round (emphasis added)
Those who believe the Earth is flat vary in the exact theories, but whether they believe in science or religious literature as the basis for their claims, a new YouGov study reveals that 2% of Americans resolutely say the earth is flat.
While an overwhelming majority of Americans (84%) believe that the Earth is round, at least 5% of the public say they used to believe that but now have their doubts.
Flat earthers find traction in their beliefs among a younger generation of Americans. Young millennials, ages 18 to 24, are likelier than any other age group to say they believe the Earth is flat (4%).
Data from YouGov Profiles suggests a link 
between belief in a flat earth and spirituality. For some flat earthers, evidence of the earth’s shape may be found in scripture – more than half of Flat earthers (52%) consider themselves “very religious,” compared to just a fifth of all Americans (20%).
