Contradiction with Leviticus 19:34
Ezra 8:8 emphasizes the returning exiles, while Leviticus 19:34 commands love for foreigners as native-born among you.
Leviticus 19:34: [But] the stranger that dwelleth with you shall be unto you as one born among you, and thou shalt love him as thyself; for ye were strangers in the land of Egypt: I [am] the LORD your God.
Contradiction with Romans 12:18
Ezra 8:8 involves gathering a specific group, while Romans 12:18 encourages peace with all men, not exclusivity.
Romans 12:18: If it be possible, as much as lieth in you, live peaceably with all men.
Contradiction with Galatians 3:28
Ezra 8:8 deals with specific lineage, whereas Galatians 3:28 states there is neither Jew nor Greek, but all are one in Christ.
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.