CLAIM: Critics of the Bible note that John writes of “the four corners of the earth” (Rev. 7:1). They argue that this demonstrates that the authors of Scripture believed in a flat earth. Is this the case?
RESPONSE: This expression (“the four corners”) is an ancient idiom to refer to the entirety of the Earth. It is similar to referring to the four points of a compass. We see the same expression in Ezekiel 7:2, which refers to the “four corners of the land.” Of course, ancient Israel wasn’t a square in any sense; instead, the author was merely trying to communicate that the end would come upon the entire nation. In other passages, the biblical authors refer to the Earth as a circle—not a square. For instance, in Isaiah 40:22, we read that God “sits above the circle of the earth.” In Proverbs 8:27, we read that God “inscribed a circle on the face of the deep” (c.f. Job 26:10). For these reasons, Osborne explains that the four corners of the Earth is “simply an idiom and no more.”
Recently, a Sports Illustrated article referred to soccer spreading to “the four corners of the earth.” No one would claim that this writer honestly believes in a flat Earth; it’s just an idiom. In the same way, a modern meteorologist might refer to the “sun rising” at 6:53 am. By this, the meteorologist obviously does not mean that the sun rotates around the Earth. Instead, this is just a common idiom.
 Osborne, Grant. Revelation. Baker Exegetical Commentary on the New Testament. Grand Rapids, MI: Baker Academic. 2002. 305.