Contradiction with Psalm 46:10
While Exodus 15:21 praises a triumphant God of war, Psalm 46:10 emphasizes being still and knowing God as a peaceful refuge.
Psalm 46:10: Be still, and know that I [am] God: I will be exalted among the heathen, I will be exalted in the earth.
Contradiction with Matthew 5:9
Exodus 15:21 celebrates victory in battle, whereas Matthew 5:9 blesses peacemakers, contrasting the focus on war.
Matthew 5:9: Blessed [are] the peacemakers: for they shall be called the children of God.
Contradiction with Romans 12:19
Exodus 15:21 depicts a God who relishes in the destruction of enemies, while Romans 12:19 advises leaving vengeance to God and pursuing peace.
Romans 12:19: Dearly beloved, avenge not yourselves, but [rather] give place unto wrath: for it is written, Vengeance [is] mine; I will repay, saith the Lord.
Contradiction with Isaiah 2:4
The exultation in Exodus 15:21 after battle success conflicts with Isaiah 2:4's prophecy of God bringing swords to plowshares, promoting peace over war.
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 James 3:18
Exodus 15:21 glorifies God as a divine warrior, which differs from James 3:18 that extols the fruit of righteousness sown in peace.
James 3:18: And the fruit of righteousness is sown in peace of them that make peace.