Contradiction with James 2:24
James emphasizes that a person is justified by works and not by faith only, contradicting Romans 4:6 which stresses justification apart from works.
James 2:24: Ye see then how that by works a man is justified, and not by faith only.
Contradiction with Romans 2:13
This verse states that the doers of the law shall be justified, which conflicts with Romans 4:6 which speaks about justification without works.
Romans 2:13: (For not the hearers of the law [are] just before God, but the doers of the law shall be justified.