A modern scientific model of the Earth's rotation, showing the planet as a globe

Azimuthal equidistant projections of the spheres of a flat Earth model depicting Antarctica as an ice wall surrounding a disk-shaped Earth.

Modern flat Earth societies consist of individuals who promote the idea that the Earth is flat rather than an oblate spheroid. Such groups date from the middle of the 20th century; some adherents are serious and some are not. Those who are serious are often motivated by pseudoscience or religious literalism.

In the modern era, through the use of social media, flat Earth theories have been increasingly espoused by individuals unaffiliated with larger groups, many of which have members around the world.

Historical

Modern flat Earth hypotheses originated with the English writer Samuel Rowbotham (1816-1884). Based on conclusions derived from the Bedford Level experiment, Rowbotham published a Zetetic Astronomy pamphlet. He later expanded into a book Earth Not a Globe, proposing the Earth is a flat disc centered at the North Pole and bounded along its southern edge by a wall of ice, Antarctica. Rowbotham is further held that the Sun and Moon were 3,000 miles (4,800 km) above Earth and that the "cosmos" was 3,100 miles (above the Earth). He also published a leaflet titled The inconsistency of Modern Astronomy and its Opposition to the Scriptures, which argued that the "Bible, alongside our senses, supported the idea that the earth was flat and immovable and this is essential. system based solely on human conjecture ".

Rowbotham and followers like William Carpenter gained attention by successful use of pseudoscience in public debates with leading scientists such as Alfred Russel Wallace. Rowbotham created a Zetetic Society in England and New York, shipping over a thousand copies of Zetetic Astronomy.

After Rowbotham's death, Lady Elizabeth Blount established a Universal Zetetic Society, whose objective was "the propagation of knowledge related to the Natural Scriptures, based on practical scientific investigation". The society published a magazine, The Earth Not a Globe Review, and remained active well into the early 20th century. A flat Earth journal, Earth: a Monthly Magazine of Sense and Science, was published between 1901-1904, edited by Lady Blount.

Criticism and Decline 

Flat Earth societies have long been criticized, due to the scientific observations that have disproved and discredited the belief. This includes photographs showing the Earth as a sphere.

Eugenie Scott called the group an example of  "extreme Biblical-literalist theology : The earth is flat because the Bible says it is flat, regardless of what science tells us."

According to Charles K. Johnson the membership of the group rose to 3500 under his leadership, but considered to decline after a fire at the house of Charles K. Johnson which destroyed all of the records and contacts of the Society, in 1997. Johnson's wife, who helped manage the membership database, shortened thereafter. Johnson himself died on March 19, 2001. (Wikipedia)

Here are their opinions based on several theories: