The answer is simple, ikester,
People who thought the earth was flat thought it up. There are many such mythologies: google "turtles all the way down" for some interesting side information (including some other major religions that do have a flat earth model).
... who ... added to creation and why.
This is a more complex question, but one that I start by asking
Charles K. Johnson, president of the International Flat Earth Research Society:
"The facts are simple," says Charles K. Johnson, president of the International Flat Earth Research Society. "The earth is flat."
As shown in a map published by Johnson, the known world is as circular and as flat as a phonograph record. The North Pole is at the center. At the outer edge lies the southern ice, reputed to be a wall 150 feet high; no one has ever crossed it, and therefore what lies beyond is unknown.
The sun and moon, in the Johnson version, are only about 32 miles in diameter. They circle above the earth in the vicinity of the equator, and their apparent rising and setting are tricks of perspective, like railroad tracks that appear to meet in the distance. The moon shines by its own light and is not eclipsed by the earth. Rather, lunar eclipses are caused by an unseen dark body occasionally passing in front of the moon.
Johnson's beliefs are firmly grounded in the Bible. Many verses of the Old Testament imply that the earth is flat, but there's more to it than that. According to the New Testament, Jesus ascended up into heaven.
It seems that this fundamentalist literal Christian believes it is part of creation. I wonder that you hate his belief so much as this post shows.
And atheists are not very much interested in the truth about it because it's works so well in making all Christians look stupid.
Only atheists that are poorly versed in logic, as this involves the logical fallacy of equivocating part with the whole while ignoring other beliefs. If you like, I will be happy to point out to any atheists that use this argument that it is a
post hoc ergo propter hoc logical fallacy.
Several mythologies\beliefs depict a flat earth
Some people believe the earth is flat
Some flat earth believers are christians
Not all christians believe the earth is flat
Not all flat-earthers are christians
There is no correlation from one to the other.
I call it: lying for the advancement of evolution.
One wonders why you hate evolution so much.
You actually agree that change in hereditary traits in populations from generation to generation occurs, and you actually agree that speciation occurs. That is evolution.
What you seem to have most trouble with are things like the age of the earth, geological evidence, and astrophysics ... not evolution. Calling all these people evolutionists is exactly the same logical error as would be committed by an atheist claiming that all creationists think the world is flat.
Enjoy.
