There is a myth that when Columbus set out on his famous voyage, people believed he would sail off the edge of the Earth. According to the myth, only the voyage of Columbus convinced people that the Earth was not flat. That myth is not true, and Earth is not flat.
The myth came from an early historical fiction work by Washington Irving in 1828. At the time of Columbus in 1492, educated Europeans knew that our planet is a sphere. The Greek philosopher Aristotle recognized that fact in 330 B.C. He observed that when lunar eclipses occurred, the shadow Earth cast on the Moon was always a semicircle. That could only happen every time if the Earth were a sphere. Also, it was easy to observe that when a ship came into shore over the ocean, the first part to be visible was the top of the sail. As it came closer, the lower part could be seen. That shows the curvature of the ocean surface.
In the early Church period, the view of a spherical Earth was widely accepted. The Christian theologian and philosopher Augustine (354-430) recognized that Earth was spherical. Theologian Thomas Aquinas (1225-1274) acknowledged that physics, astronomy, and mathematics had proven that Earth is a sphere.
However, the Quran (609-632) says that the Earth was “laid out,” “spread out,” or “made flat” depending on how it’s translated. In the sixteenth century, a Sunni commentary stated that most Muslim scholars took those words to mean the Earth is flat. Chinese society did not let go of the concept of a flat Earth until the seventeenth century when Jesuit scholars brought their teaching to that country.
As Islam becomes more dominant in America, Muslims have begun to attack Christianity and the Bible with increasing frequency. There are several videos on the web that claim that the Comforter mentioned in John 14:26 is Muhammad. The word Muhammad means “praised one” and the claim is that the original word in the Greek was “perikleitos” which means “famous everywhere” or “renowned,” but that it was corrupted into “parakletos” meaning “counselor.” So how do you and I, not being experts in Greek, answer this question?
The answer is to look at the context of the passage. You don’t have to be a Greek expert to see that this passage is not dealing with a physical human who was a military leader. In John 14:23 Jesus talks about his disciples loving God and promising that the Godhead would dwell with those who love God. He then in verse 26 tells them that He would be sending “the Comforter, which is the Holy Spirit” who would teach them all things. This statement is right after Judas had left and before Jesus was arrested. The reference is not to a claimed prophet who would live some 600 years later. (Islamic teaching is that Muhammed began getting messages from Gabriel in A.D. 610.) Verse 26 also tells us that the Comforter would come in the name of Jesus, and no Muslim would agree that Muhammad came in the name of Jesus.
Another issue is the Muslim claim that the biblical documents have been corrupted. The problem with that claim is that all of these documents were written before Muhammad was born, and copies of the manuscripts exist that are much older than A.D. 610. Complete manuscripts of John 14 dating from the third or fourth century exist. The question would have to be, “At what time were the documents corrupted?” It would have to be before the third century and yet the Quran dates to the seventh century.