Contradiction with Exodus 14:14
God instructs His people to remain still and let Him fight for them, as opposed to taking action.
Exodus 14:14: The LORD shall fight for you, and ye shall hold your peace.
Contradiction with 2 Chronicles 20:17
Here, the people are told they will not need to fight in the battle, contradicting the active engagement instructed in Joshua 8:18.
2 Chronicles 20:17: Ye shall not [need] to fight in this [battle]: set yourselves, stand ye [still], and see the salvation of the LORD with you, O Judah and Jerusalem: fear not, nor be dismayed; to morrow go out against them: for the LORD [will be] with you.
Contradiction with Matthew 5:44
Jesus teaches to love and pray for enemies, contrasting with the act of taking aggressive military action.
Matthew 5:44: But I say unto you, Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you;
Contradiction with Romans 12:19
This verse advises believers to not seek revenge but leave it to God's wrath, against the directive in Joshua for combat.
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.