It is argued that Christ directly contradicts the Old Testament in Matthew 5:38-39 and that his command is cleverly undone by Paul in Romans 12:19. But as the 'right cheek' context tells us (along with study of relevant source material), what Christ contradicts here is the false application of the OT to personal matters, when the original law was made in the context of vested authorities delivering equitable punishments. Christ is not contradicting the OT, but a wayward application of it; Paul is not 'undoing' anything said by Christ but is reminding people not to take personal vengeance, just as Jesus did -- and pointing out, as Jesus did in other contexts, that God's judgment for sin will eventually come upon people who do wrong.

Critics sometimes assert that Jesus taught a loving religion in strict opposition to the Old Testament, and suggest that Paul actually corrupted Christ's teachings, offering two comparisons as evidence.

The first, a comparison of Matt. 5:43-45 and Romans 12:20:
> Ye have heard that it hath been said, Thou shalt love thy neighbour, and hate thine enemy. But I say unto you, Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you; That ye may be the children of your Father which is in heaven: for he maketh his sun to rise on the evil and on the good, and sendeth rain on the just and on the unjust.

> Therefore if thine enemy hunger, feed him; if he thirst, give him drink: for in so doing thou shalt heap coals of fire on his head.

It is argued that Paul advocates what he calls love in order to defeat one's enemies and thereby undoes Christ's work and returns us to the pre-Christ era.

As Klassen shows in his article "Coals of Fire: Sign of Repentance or Revenge?" (New Testament Studies 9, 1963, 337-50) the phrase in Proverbs is alluding to an Egyptian ritual of repentance in which the subject willingly carried embers in a bowl on their head as a public sign of repentance. It is unlikely that people in NT times were aware of this detail, but the Targum commentaries Paul would have been familiar with did still grasp that the person in Proverbs was a former enemy who had been turned into a friend.

The second offering compares Matt. 5:38-39 with Romans 12:19:
> Ye have heard that it hath been said, An eye for an eye, and a tooth for a tooth: But I say unto you, That ye resist not evil: but whosoever shall smite thee on thy right cheek, turn to him the other also.

> Dearly beloved, avenge not yourselves, but rather give place unto wrath: for it is written, Vengeance is mine; I will repay, saith the Lord.

Here we are told that Christ "directly contradicts" the OT and that his command is "cleverly undone by Paul" -- but as the "right cheek" context tells us (along with study of relevant source material), what Christ contradicts here is the false application of the OT to personal matters, when the original law was made in the context of vested authorities delivering equitable punishments. Christ is not contradicting the OT, but a wayward application of it; Paul is not "undoing" anything said by Christ but is reminding people not to take personal vengeance, just as Jesus did -- and pointing out, as Jesus did in other contexts, that God's judgment for sin will eventually come upon people who do wrong.