Most of us have read or heard references to flat-earthers. I have always assumed they are some tiny tongue-in-cheek group which is just playing out an elaborate joke on the rest of us. The Greeks figured out by 300 A.D. that the earth was round, and this tidbit was incorporated into medieval scholarship, so there has never been much religious or traditional impetus for a flat earth. I was therefore a bit surprised to learn that flat earth beliefs are very serious to many folks, and that such beliefs seem to be on the rise.

From Wikipedia:

In 2020, it was reported that based on polling by Datafolha, 7% of Brazilians believed in a flat Earth. A 2018 YouGov poll found that around 4% of the population of the United States believed in flat Earth while the POLES 2021 Survey found around 10% of the United States population believed that the Earth is flat. A 2019 YouGov survey found that around 3% of British people supported flat Earth.

Digging into that 2018 YouGov poll finds that 2% of Americans resolutely say the earth is flat, but many others who lean towards a round earth are not quite sure. Flat-earthism is more prevalent in Millennials than in older folks, only 66% of Millennials firmly believe the earth is round :

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%).

Apparently, a YouTube channel launched in 2015 by real-life pinball wizard Mark Sargent (“…a competitive video game player, winning one virtual pinball tournament”), which has amassed over two million views, has played a role in popularizing flat earth beliefs. In his brand of geography, the center of the earth-disk is roughly the North Pole, and the edge of the earth-disk lies in what we normally think of the extreme south, and is surrounded by an ice-wall. Several basketball players (Kyrie Irving, Wilson Chandler, Draymond Green) and a rapper (B.o.B) have come out in favor of flatness. The NASA conspiracy of a round earth is crumbling…

 I think some of this flat-earth polling is just ignorance, especially those who are not sure. But there are those who “have their reasons”, often citing various (pseudo) scientific arguments to support their beliefs:

Research by Carlos Diaz Ruiz and Tomas Nilsson on the arguments that flat Earthers wield, shows three factions, each one subscribing to its own set of beliefs.

The first faction subscribes to a faith-based conflict in which atheists use science to suppress the Christian faith. … their arguments use the Scripture – word-by-word – to support an argument that enables God to really exist.

The second faction believes in an overarching conspiracy for knowledge suppression. Building upon the premise that knowledge is power, the flat Earth conspiracy argues that a shadowy group of “elites” control knowledge to remain in power. In their view, lying about the fundamental nature of the Earth primes the population to believe a host of other conspiracies. …

The third faction believes that knowledge is personal and experiential. They are dismissive of knowledge that comes from authoritative sources, especially book knowledge. 

Belief in geocentricity (i.e., that the earth is stationary and the sun goes around the earth) is even more widespread than belief in a flat earth. From Wikipedia:

According to a report released in 2014 by the National Science Foundation, 26% of Americans surveyed believe that the Sun revolves around the Earth.  Morris Berman quotes a 2006 survey that show currently some 20% of the U.S. population believe that the Sun goes around the Earth (geocentricism) rather than the Earth goes around the Sun (heliocentricism), while a further 9% claimed not to know. Polls conducted by Gallup in the 1990s found that 16% of Germans, 18% of Americans and 19% of Britons hold that the Sun revolves around the Earth.  A study conducted in 2005 by Jon D. Miller of Northwestern University, an expert in the public understanding of science and technology,  found that about 20%, or one in five, of American adults believe that the Sun orbits the Earth.  According to 2011 VTSIOM poll, 32% of Russians believe that the Sun orbits the Earth.

Geocentrism seems particularly driven by religious concerns, although I think the polls also heavily reflect plain ignorance. There are passages in the Bible which, if taken literally, seem to mandate a stationary earth and a moving sun. The Roman Catholic church has tiptoed away from its condemnation of Galileo four hundred years ago, and essentially accepted his contention that such passages were never intended to be taken literally. Nevertheless, Catholic layman Robert Sungenis has vigorous argued for geocentricity and Bible literalism, publishing books such as Galileo Was Wrong. On the fundamentalist Protestant side, there is the Association for Biblical Astronomy, with its web site www.geocentricity.com. They make arguments to dismiss the usual scientific conclusions on this matter.

Geocentricity is somewhat poignant for me, because a good friend of mine from college later became deeply attached to it, to the point that he rejected my thinking as apostate when I disagreed. He was a bright guy and an Ivy League graduate. Which just goes to show that fringe beliefs can have unexpected appeal.