Festal Letter 39

Festal Letter 39, written by Athanasius of Alexandria in 367 for the annual Easter announcement to the churches under his authority, is the primary early Christian text listing the twenty seven books that would become the New Testament canon together and distinguishing them from other books he says may be read for edification but are not canonical scripture. Its strength is that it is the earliest surviving list matching the later settled New Testament canon exactly, a genuine primary landmark in the canon's history rather than a later historian's account of when the list stabilized. Its limit is that Athanasius's letter states his own view as a single influential bishop, not a formal ecumenical council ruling binding on the whole Church at the time it was written, so a claim that the New Testament canon was formally and universally closed in 367 by this letter alone overstates its actual authority in its own period.