Contradiction with Matthew 15:24
This verse where Jesus says He was only sent to the lost sheep of Israel seems exclusive, while Romans 15:8 suggests a ministry to both Jews and Gentiles.
Matthew 15:24: But he answered and said, I am not sent but unto the lost sheep of the house of Israel.
Contradiction with Acts 13:46
Paul and Barnabas speak to turning to the Gentiles due to Jewish rejection, which contrasts with the perception of Jesus as a servant to the circumcision in Romans 15:8.
Acts 13:46: Then Paul and Barnabas waxed bold, and said, It was necessary that the word of God should first have been spoken to you: but seeing ye put it from you, and judge yourselves unworthy of everlasting life, lo, we turn to the Gentiles.
Contradiction with Galatians 3:28
This verse talks about no division between Jew and Gentile in Christ, which appears to contradict emphasis on Jesus being a minister to the Jews in Romans 15:8.
Galatians 3:28: There is neither Jew nor Greek, there is neither bond nor free, there is neither male nor female: for ye are all one in Christ Jesus.