Didache

The Didache opens with the Two Ways, a stark ethical framework, "there are two ways, one of life and one of death, and there is a great difference between the two ways," that lays out the way of life through a dense sequence of moral instruction closely echoing the Sermon on the Mount and the way of death through a long list of vices to avoid, material scholars believe drew on an older Jewish ethical teaching document also reflected in the roughly contemporary Epistle of Barnabas.

The text then turns practical, giving what may be Christianity's earliest surviving instructions on baptism, preferring immersion in "living water," meaning naturally running water, but explicitly permitting pouring water over the head three times if sufficient water for immersion cannot be found, a flexible, pastorally realistic provision; on fasting, prescribing Wednesdays and Fridays specifically to distinguish Christian practice from the Monday and Thursday fasts of "the hypocrites," a barely veiled reference to Pharisaic Jewish practice; and on the Eucharist, preserving prayers of thanksgiving over the cup and the bread that are among the oldest eucharistic prayer texts to survive outside the New Testament itself. Later chapters address how a young, still loosely organized church should evaluate traveling apostles and prophets, warning against those who overstay their welcome or ask for money, and the whole text closes with a short, urgent warning about deceivers appearing before the world's end.

For most of Christian history the Didache was known only by title and a handful of brief quotations preserved in other early Christian writers, until the Greek Orthodox metropolitan Philotheos Bryennios discovered a complete copy in 1873 in the library of the Monastery of the Holy Sepulchre in Constantinople, bound into a manuscript called the Codex Hierosolymitanus dated 1056 CE, and published it a decade later in 1883, a rediscovery that ranks among the most significant textual finds in the study of earliest Christianity, since it offered scholars a direct window into church practice and organization from a period the New Testament itself only partially describes. Its canonical fortunes in antiquity were genuinely unsettled: Eusebius, writing his history of the church in the early 4th century, placed it among texts some communities read as scripture and others firmly rejected, and it was ultimately excluded from the New Testament that took final shape in the following centuries, even though some Eastern canon lists continued to reference material close to it much later.

The text's picture of church order, itinerant apostles and prophets still moving between communities, no fixed episcopal hierarchy yet firmly established, and baptism and Eucharist practiced with more local flexibility than later, more standardized liturgy allowed, has made it an important and much debated source for historians reconstructing how the earliest Christian communities were actually organized before more centralized church structures took hold.