Didachē appears 30 times in the NT. It derives from didaskō (G1321), 'to teach.' The word covers both the act of teaching and the content being taught. Jesus's teaching is repeatedly described as didachē — and the crowd's consistent response was astonishment, 'because he taught as one who had authority, and not as their teachers of the law' (Matthew 7:28-29). The apostles' teaching (didachē tōn apostolōn) was one of the four pillars of the early Jerusalem community (Acts 2:42). False teaching (heterodidaskalia) is a major concern of the Pastoral Epistles.
The NT takes sound didachē seriously because teaching shapes identity, behavior, and community. Romans 6:17 describes believers as those who 'have wholeheartedly obeyed the form of teaching [typos didachēs] to which you were entrusted.' 2 Timothy 3:16 says all Scripture is 'profitable for teaching [didaskalia].' The 'Didache' (early second century) — an early church manual — took its name from this word, showing how central instructional tradition was. In Revelation 2:14-15, 24, false didachē (the teaching of Balaam; the teaching of the Nicolaitans) is cited as a lethal threat. Sound teaching is not optional — it is the lifeblood of healthy community.