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 too is just a common idiom.
Finally, it’s rather odd that critics flock to this passage when the very next verse refers to the “rising of the sun” (Rev. 7:2). Why don’t critics balk at this expression? Do they really believe that the Earth is stationary, and the sun moves over the horizon? Of course not. These are all idiomatic expressions that have been common throughout history.
 Grant R. Osborne, Revelation, Baker Exegetical Commentary on the New Testament (Grand Rapids, MI: Baker Academic, 2002), 305.