Contradiction with Isaiah 2:4
While Luke 21:10 speaks of nations rising against one another, Isaiah 2:4 talks about nations not learning war anymore and living in peace.
Isaiah 2:4: And he shall judge among the nations, and shall rebuke many people: and they shall beat their swords into plowshares, and their spears into pruninghooks: nation shall not lift up sword against nation, neither shall they learn war any more. [pruninghooks: or, scythes]
Contradiction with Matthew 5:9
Luke 21:10 predicts conflict among nations, whereas Matthew 5:9 blesses peacemakers, implying a focus on peace over conflict.
Matthew 5:9: Blessed [are] the peacemakers: for they shall be called the children of God.
Contradiction with Romans 12:18
Luke 21:10 foresees wars among nations, yet Romans 12:18 encourages living peacefully with all men.
Romans 12:18: If it be possible, as much as lieth in you, live peaceably with all men.