In 535, the Christian monk Cosmas wrote his Christian Topography.
Using Bible verses, he "proved" the earth was a flat rectangle, bordered by a "frame" of oceans. His primary sources: Genesis 1, Exodus 25, and Hebrews 9.
Though admitting a North and a South direction, he had no North or South Pole. Also, he proved that the parallelogram's length was double its width (following Moses' description of the Tabernacle table, which was an rectangular image of the earth, 2 cubits by 1 cubit).
Why bring all of this up? Because it reminds me of some of our current "dogmatic" views of mathematics education. Luckily we have moved beyond the "flat-earth" mentality; it is time we do the same in terms of what mathematics is and how it should be learned!