Cyril, bishop of Jerusalem writes in his Catechetical Lectures: “For concerning the divine and holy mysteries of the Faith, not even a casual statement must be delivered without the Holy Scriptures; nor must we be drawn aside by mere plausibility and artifices of speech. Even to me, who tell thee these things, give not absolute creedence, unless thou receive the proof of the things which I announce from the Divine Scriptures. For this salvation which we believe depends not on ingenious reasoning, but on demonstration of the Holy Scriptures.” (IV:17)
Notice that Cyril does not appeal to his authority as a bishop but rather insists that all Christians must search the Divine Scriptures for themselves. They cannot take his word for it unless they have demonstration from the Holy Scriptures. Salvation and those things necessary for it do not depend upon “ingenious reasoning.” The Scriptures are clear and sufficient to serve as the ultimate, infallible authority for matters of faith and piety.