In his First Apology, Justin wrote the following:
For
from Jerusalem there went out into the world, men, twelve in number, and these
illiterate, of no ability in speaking: but by the power of God they proclaimed
to every race of men that they were sent by Christ to teach to all the word
of God (Gk: διδάξαι πάντας τὸν τοῦ θεοῦ λόγον). (First Apology, 39 [ANF 1:175-76])
This shows us that “the word of
God” for Justin is not exhausted by inscripturated revelation, as the apostles
were commissioned “to teach to all the word of God” prior to the inscripturation
of a single book of the New Testament.
For more, see:
Not
By Scripture Alone: A Latter-day Saint Refutation of Sola Scriptura
