Why is the earth flat?

The storyteller Washington Irving almost singlehandedly invented the rumor, in 1828, that Christopher Columbus was an American hero who woke the church and people of the Middle Ages to the reality of a spherical globe. Though this fiction has often been repeated in modern children's books, Western opinion has not supported flat earth ideas since at least Ptolemy, and mainstream Christian groups have never espoused this, even in the Middle Ages.