Contradiction with Matthew 10:5-6
These verses describe Jesus instructing the apostles to go only to the lost sheep of Israel, which contradicts Acts 15:23 addressing Gentile believers.
Matthew 10:5-6: These twelve Jesus sent forth, and commanded them, saying, Go not into the way of the Gentiles, and into [any] city of the Samaritans enter ye not:
Contradiction with Acts 10:28
Peter explains it is unlawful for a Jew to associate with a Gentile, contradicting the inclusive message of Acts 15:23.
Acts 10:28: And he said unto them, Ye know how that it is an unlawful thing for a man that is a Jew to keep company, or come unto one of another nation; but God hath shewed me that I should not call any man common or unclean.
Contradiction with Galatians 2:11-12
Paul opposes Peter for withdrawing from Gentiles, showing tension with the inclusive stance reflected in Acts 15:23.
Galatians 2:11-12: But when Peter was come to Antioch, I withstood him to the face, because he was to be blamed.
Contradiction with Exodus 34:16
Warns against making covenants with Gentiles, which contrasts with extending a letter to them as in Acts 15:23.
Exodus 34:16: And thou take of their daughters unto thy sons, and their daughters go a whoring after their gods, and make thy sons go a whoring after their gods.