Contradiction with Matthew 5:44
Joel 3:4 talks about retribution against Tyre and Sidon, while Matthew 5:44 instructs to love your enemies and pray for those who persecute you.
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
Joel 3:4 implies taking vengeance, while Romans 12:19 advises against seeking personal revenge.
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 Proverbs 20:22
Joel 3:4 suggests repayment for deeds, whereas Proverbs 20:22 teaches to wait for the Lord for deliverance instead of seeking revenge.
Proverbs 20:22: Say not thou, I will recompense evil; [but] wait on the LORD, and he shall save thee.