The Bible told us the earth was round when most men believed it to be flat (Isaiah 40:22).
MOST people KNEW the earth was round. A Greek feller named Eratosthenes PROVED it several hundred years before Christ by measuring the sun’s shadow at different latitude in Egypt. He even figured out its diameter within a few hundred miles.
The “flat-earth” theory was poppycock. People in the Middle Ages knew it was round. You can tell by watching a sailing ship sail out to sea. If the earth is small,the ship would get smaller and smaller and disappear. Medieval mariners knew that the hull disappears first, then the lower masts and spars and then the upper masts and spars. Could only happen if the earth was round.