Contradiction with Deuteronomy 7:2
This verse advises the Israelites to destroy the nations and make no treaties with them, contradicting Acts 11:12 by discouraging interaction with foreigners.
Deuteronomy 7:2: And when the LORD thy God shall deliver them before thee; thou shalt smite them, [and] utterly destroy them; thou shalt make no covenant with them, nor shew mercy unto them:
Contradiction with Matthew 10:5
Jesus instructs His disciples not to go to the Gentiles, which contradicts Acts 11:12 where Peter is told to go with those from Caesarea without doubting.
Matthew 10:5: 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 2 Corinthians 6:14
This advises not being yoked together with unbelievers, conflicting with the direction in Acts 11:12 to accompany those who are not Jewish believers.
2 Corinthians 6:14: Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness?