“group will rise against group.” The Greek word translated as “group” is ethnos (#1484 ἔθνος), which has a large number of different meanings. These include the meaning that we feel fits the best in this context: a group of people united by kinship, culture, or traditions. The other meanings of ethnos include: a group or multitude (of people or animals) that is living together or closely associated; the whole human race (thus “people”); a race; a nation; a company, troop, or mass of people; a group of the same nature or ancestry; the unbelievers in contrast to God’s chosen people; also, in the New Testament ethnos is sometimes used for Gentile Christians in contrast to Jewish Christians.
The exact meaning of ethnos has to be determined by the context in which it is used. In this case, Jesus is speaking of the end times and saying that ethnos will rise and fight against ethnos, and the meaning that fits best is people groups that are united by kinship, culture, traditions, and belief systems. Lenski basically agrees and says the term refers here to “a body of people that is held together by the same customs.” Although ethnos has been traditionally translated “nation,” that is not its best use in this context. One reason for that is today most of what we call “nations” would be called “kingdoms” in the biblical culture, even though they are not strictly ruled by a “king,” and thus would be included in the next phrase, “kingdom against kingdom.” That leaves the phrase ethnos against ethnos to refer to smaller people groups.
What we see in the world around us is “group against group” and “kingdom against kingdom” (more properly, “nation against nation”). While it is true that nations (kingdoms) are fighting each other, such as North versus South Korea, or Russia versus the Ukraine, the greater fighting seems to be group against group. In the USA, gangs are fighting other gangs, and there is also much racial violence. All over Europe, anti-Jewish groups are rising up and terrorizing Jews. In the Moslem world, Shiites are fighting Sunnis. It seems to be group versus group all over the world. These “groups” are people groups that are united by kinship, culture, traditions, and belief systems, and the “group versus group” mentality is intensifying around the world.
It is decidedly difficult to translate the word ethnos as it is used in Matthew 24, Mark 13, and Luke 21 into English. A few modern translations are getting away from the word “nation,” which is misleading, and translating ethnos as “people” or “peoples” (cp. CJB, MGI). While “people” is certainly better than “nation,” the reader may misunderstand and think that Jesus was speaking of general violence between individuals. While there will certainly be violence by individuals in the end times, that is not what the verse is referring to. On the other hand, we must understand “group” as referring to a group that is connected by lineage, race, creed, tradition, or belief, and not just a gather at the local store. Each member of the group is definitely connected to the group. Perhaps 50 years ago, “tribe” would have communicated the meaning well, but today “tribe” is more exclusively used of native tribes. Other words that come close are “sect,” but that puts too much emphasis on belief, and “ethnic group,” but that puts too much emphasis on race. Jesus was referring to the fact that as we approach the end, groups will rise up against each other: racial and ethnic groups, religious groups, socio-economic groups, and so forth. The concept of ethnos as a connected group of people was much easier to understand in the ancient world, when governments were often adversarial to people and families, and families were both big and the foundation of the culture. In the ancient world much more than today there was “safety in a multitude,” and people grouped based on family, ancestry, and creed.