The idea that intelligent people in the Middle Ages believed the Earth was flat is false. Maybe some illiterate peasants did, but not anyone with any schooling. The fact that the Earth was a sphere was known to the ancients.
No it isn't. Many people and scientists did believe the earth was flat in the middle ages.
In order for your statement to be true, no intelligent person in the middle ages would have believed in the earth being flat.
You are welcome to try again.