What does Matthew 5:38 mean?

Jesus moves on to another "you have heard," "but I say" topic. This time, He expects His audience has heard the "law of retaliation," often summed up as an eye for an eye and a tooth for a tooth. This comes from God's system of justice for the Israelites as described in Deuteronomy 19:21, "Your eye shall not pity. It shall be life for life, eye for eye, tooth for tooth, hand for hand, foot for foot."

It's a testament to Christ's influence in changing mankind that modern readers often see "eye for an eye" as vicious or harsh. The reason God gave that law was to prevent escalation, including excessive punishment for crimes. Human nature is to retaliate "plus one." In other words, if you slap me, I'll punch you. If you stab me, I'll shoot you. This pattern of revenge is what turns petty insults into riots, and minor crimes into wars. God's rule for Israel was to limit retaliation and punishment to a fair equivalent of harm. God's teaching about "eye for an eye" was meant to limit violence, not encourage it.

Christ's teaching on the matter, given in the next few verses, reveals the true intent God has for His people. So far as it goes between individual people, God's will is that we do not take revenge, at all (Matthew 5:39). This doesn't mean being weak or passive in the face of blatant violence (Luke 22:36), but it does prohibit seeking to "get even" when we're insulted or abused (Romans 12:19).