The Greek adjective athemitos (ἀθέμιτος) means unlawful, forbidden, contrary to divine law, or abominable. It comes from the alpha-privative and themis (divine law, right). It describes what violates established divine or moral order.
Athemitos appears in two powerful New Testament contexts. Peter's vision in Acts 10 drives him to Cornelius's house, where he declares: 'You are well aware that it is against our law (athemiton) for a Jew to associate with or visit a Gentile. But God has shown me that I should not call anyone impure or unclean.' Then in 1 Peter 4:3, the word describes the pagan lifestyle believers have left behind. The Gospel radically redefines what is 'unlawful' — not by ethnic purity codes but by the holiness of the new covenant.