Contradiction with James 2:24
This verse emphasizes justification by works, contrasting 2 Corinthians 6:1 where grace is emphasized without works.
James 2:24: Ye see then how that by works a man is justified, and not by faith only.
Contradiction with Galatians 2:21
Suggests that righteousness can come through the law, which contrasts with 2 Corinthians 6:1's emphasis on not receiving God's grace in vain.
Galatians 2:21: I do not frustrate the grace of God: for if righteousness [come] by the law, then Christ is dead in vain.
Contradiction with Romans 4:4
Describes blessings as a result of works, opposite of 2 Corinthians 6:1's focus on grace without works.
Romans 4:4: Now to him that worketh is the reward not reckoned of grace, but of debt.