In 1 Timothy 6.3, Paul warns Timothy to be on the lookout lest
…τις ἑτεροδιδασκαλεῖ καὶ μὴ προσέρχεται ὑγιαίνουσι λόγοις, τοῖς τοῦ κυρίου ἡμῶν Ἰησοῦ Χριστοῦ, καὶ τῇ κατ’ εὐσέβειαν διδασκαλίᾳ….
“…anyone teach something other [than true doctrine] and does not agree with healthful words–those of our Lord Jesus Christ–and the teaching that accords with εὐσέβεια….”
The word εὐσέβεια can have a variety of meanings: piety, [true] religion, godliness. And whatever other connotations it may have here, 1 Paul at least surely means us to connect it with an earlier use of εὐσέβεια in this letter, in 3.16 (the word is used eight times altogether in the letter):
καὶ ὁμολογουμένως μέγα ἐστὶν τὸ τῆς εὐσεβείας μυστήριον· Ὃς ἐφανερώθη ἐν σαρκί, ἐδικαιώθη ἐν πνεύματι, ὤφθη ἀγγέλοις, ἐκηρύχθη ἐν ἔθνεσιν, ἐπιστεύθη ἐν κόσμῳ, ἀνελήμφθη ἐν δόξῃ.
And great, undeniably, is the mystery of εὐσέβεια: Who was manifested in flesh, justified in spirit, seen by angels, proclaimed among the nations, believed on in the world, taken up in glory.
The relative clause reads like a confession of faith, a dense and highly compressed credo. Thus τὸ τῆς εὐσεβείας μυστήριον has an objective character, something like “the mystery of the doctrine of God incarnate”–the apostolic witness, that is, to the person and work of Jesus Christ.
What would this mean for 6.3, taking one thing with another? It would mean that Timothy is to evaluate teachings based upon a standard that is twofold: viz., the words of Christ himself and the apostolic witness to Christ. And, as we have seen in a number of other New Testament passages as well, 2 this standard is taken to be objective, publicly accessible, and serviceable for the task of comparative judgment. Nothing more is expressed or implied to be needful.
Timothy–and, by extension, those who find themselves addressed by the letter–are presumed, then, to be competent to make the judgment that Paul requires. Jesus’ words, and the “religion” that bears witness to Jesus, are there and are intelligible for those who would hear them. More than that, they are enough. They are sufficient for the task at hand. 3
Voila: in two verses–for scriptura sancta sui ipsius interpres and scriptura scripturae interpres–we have the core of the doctrines of perspicuity and sufficiency.
One might say more: it is only in the way just sketched–that is, by conforming its teaching to the words of Jesus and the apostolic confession of Jesus–that the church is a στῦλος καὶ ἑδραίωμα τῆς ἀληθείας, a pillar and foundation of the truth, as Paul calls it in 3.15. For what does a foundation or support, a ἑδραίωμα, do? It holds something up so that it is visible. If is does not do that–if it does not hold something up–it serves no purpose.
And so: the church, if it is to be the church, holds up and presents Jesus Christ, who is himself the truth, to the hearing of faith . This Christ, Paul tells Timothy, must be the Christ of Christ’s own words and the words of his apostles; anything else is a counterfeit, and sinking sand.