Contradiction with Romans 3:28
While Deuteronomy 4:5 emphasizes keeping the law, Romans 3:28 argues that a man is justified by faith without the deeds of the law.
Romans 3:28: Therefore we conclude that a man is justified by faith without the deeds of the law.
Contradiction with Galatians 2:16
Deuteronomy 4:5 stresses the importance of following the law, yet Galatians 2:16 states that a person is not justified by the works of the law, but by faith in Jesus Christ.
Galatians 2:16: Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ, even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law: for by the works of the law shall no flesh be justified.
Contradiction with Ephesians 2:8-9
Whereas Deuteronomy 4:5 focuses on law observance, Ephesians 2:8-9 claims salvation is through grace by faith, not by works, so no one can boast.
Ephesians 2:8-9: For by grace are ye saved through faith; and that not of yourselves: [it is] the gift of God:
Contradiction with Hebrews 8:13
Deuteronomy 4:5 speaks of adhering to the law given by God, but Hebrews 8:13 suggests the old covenant, and thus the old laws, are obsolete.
Hebrews 8:13: In that he saith, A new [covenant], he hath made the first old. Now that which decayeth and waxeth old [is] ready to vanish away.