How should unbelievers be treated?

Deuteronomy 13 is not about unbelievers in general. It concerns an Israelite, a member of the covenant people living under God as their King, who secretly tries to lead others to “serve other gods” (13:6). The same chapter deals with a false prophet (13:1-5) and with a town that turns to idols (13:12-18), and it requires a careful enquiry before judgment (13:14). Any death sentence needed two or three witnesses (17:6). In Israel, where God was the nation’s King and lawgiver, turning his people to other gods was treason against the covenant on which the nation stood (Exodus 20:2-3). The law did not tell Israel to put foreigners in other lands to death for what they believed. Foreigners living in Israel were bound by some of the same laws, for example against giving a child to Molech and against blasphemy (Leviticus 20:2; 24:16), but no one was forced to become an Israelite, and the stranger who lived in Israel was to be loved “as thyself” (Leviticus 19:34).

2 Corinthians 6:14-17 does not tell Christians to shun unbelievers. It forbids being “unequally yoked together with unbelievers”, bound in partnerships that would draw a believer into idolatry: “what agreement hath the temple of God with idols?” (6:16). Paul had already said that he did not mean believers to avoid the unbelievers of this world, “for then must ye needs go out of the world” (1 Corinthians 5:10), and he told those already married to unbelievers to stay with them (7:12-13).

Matthew 5:44 gives the Christian’s duty to everyone outside the faith, including those who are hostile: “Love your enemies, bless them that curse you, do good to them that hate you”. Paul says the same: “Bless them which persecute you: bless, and curse not” (Romans 12:14). When James and John wanted to call down fire on a Samaritan village that would not receive Jesus, he rebuked them (Luke 9:54-55). The church was never given the sword of Israel’s courts. Its sternest discipline, for its own members, is to put them out of its fellowship, while “them that are without God judgeth” (1 Corinthians 5:12-13). So the passages answer different questions: Israel’s law against treason within a nation under God, the church’s rule against binding ties with idolatry, and every believer’s duty of love to all.

The seriousness remains

Some stress that the New Testament does not make light of what Deuteronomy punished. Hebrews recalls that “He that despised Moses’ law died without mercy under two or three witnesses” and warns of worse punishment for those who trample on the Son of God (Hebrews 10:28-29). The difference is that the judgment is now left to God.

Christians have not always kept to this. In later centuries some appealed to Deuteronomy 13 to justify putting heretics to death, a use that most Christians now reject as a failure to see the difference between Israel’s theocracy and the church.