κοινόω

I make unclean, regard as unclean

Definition

The verb κοινόω (koinoō) fundamentally means 'to make common' or 'to defile,' signifying a state of ritual impurity or moral contamination. In its active voice, it describes the act of rendering something ceremonially unclean or polluting it, as seen in Jesus' teaching that what comes out of a person defiles them (Mark 7:15, 20). In the middle voice, it means 'to consider or treat as unclean,' which is pivotal in Acts 10:15 where God declares to Peter, 'What God has made clean, do not call common.' This dual sense captures both the objective state of defilement and the subjective human judgment of it.

Biblical Usage

This word is used exclusively in the Gospels of Matthew and Mark and the book of Acts, primarily in debates about ritual purity. In Matthew 15:11, 18, 20 and Mark 7:15, 18, 20, 23, Jesus uses it to contrast external, ceremonial defilement with internal, moral defilement originating from the heart. In Acts, it appears only in Peter's vision (Acts 10:15; also implied in 11:9), where it is used metaphorically to overturn Jewish dietary laws and, by extension, the barrier between Jews and Gentiles, declaring that God has cleansed what was once considered 'common.'

Etymology

Derived from the adjective κοινός (koinos, G2839), meaning 'common,' 'shared,' or 'ordinary.' The verb form κοινόω thus originally meant 'to make common' or 'to share.' In Jewish and Septuagint Greek, 'common' took on the negative connotation of 'profane' or 'ceremonially unclean,' as opposed to 'holy' or 'set apart' (ἅγιος, hagios). This development reflects the Hellenistic Jewish worldview where what was not dedicated to God was considered 'common' and potentially defiling.

Semantic Range

This word is theologically significant as it sits at the crossroads of law, grace, and gospel inclusion. Jesus' use redefines purity from an external, ritual observance to an internal matter of the heart (Mark 7:20-23). In Acts, God's command not to 'call common' what He has cleansed (Acts 10:15) is the divine warrant for the inclusion of the Gentiles into the people of God, dismantling the barrier of the Mosaic ceremonial law. Understanding κοινόω enriches reading by highlighting the New Testament's shift from ritual purity to the transformative, heart-level purity made possible through Christ.

In its original Jewish cultural setting, the concept of being 'common' (κοινός) was closely tied to the Levitical purity laws. Objects, foods, and people could be rendered 'unclean' or 'common,' making them unfit for worship or fellowship with the holy community. This stood in stark contrast to the broader Greco-Roman use of κοινός, which simply meant 'shared by all' without negative moral weight. The New Testament usage, especially in Jesus' teachings and Peter's vision, directly challenges and reinterprets these Jewish cultural norms of separation.

μιαίνω (miainō, G3392) — Often a stronger term for moral defilement or staining, used in contexts of serious sin (Titus 1:15). μολύνω (molynō, G3435) — To soil or defile, often in a moral sense, used for defiling one's garments (Revelation 3:4) or conscience (1 Corinthians 8:7).

Word Details

Scripture References