"What is the mark of a faithful soul? To be in these dispositions of full acceptance on the authority of the words [of the Scripture], not venturing to reject anything nor making additions. For, if 'all that is not of faith is sin,' as the Apostle says, and 'faith cometh by hearing and hearing by the word of God,' then everything outside Holy Scripture, not being of faith, is sin." —
St. Basil the Great, Moralia (rule 80, ch. 22)
Today, the Church remembers the witness of St. Basil the Great.