George Leo Haydock, on 1Tim 6:20

O Timothy, keep that which is committed [11] to thy trust. He does not mean his charge of bishop, nor the graces of God, but the true and sound doctrine delivered to him either by writing or word of mouth, according to the common interpretation. See St. Chrysostom, Vincentius Lirinensis, Commonitorii, chap. xvii. This is confirmed by the following words, avoiding the profane novelties [12] of words: (in the Greek empty, vain, babbling). The apostle here condemns new words, which change the doctrine; but sometimes to express the ancient doctrine, new words may be found necessary, as those of trinity, incarnation, consubstantiality, transubstantiation, &c. as St. Athanasius, St. Augustine, and others observed. See 2 Timothy i. 14. — Oppositions of knowledge falsely so [13] called. St. Chrysostom understands in particular the errors of the Gnostics, so called from the same Greek word, who were the successors of Simon Magus. But they perhaps not having the name when St. Paul wrote, we may rather understand heretics in general, who all pretend to an uncommon knowledge in Scriptures, when they follow their own private judgment, and so fall from the faith. (Witham) — Keep the deposit, viz. of faith, which has been committed to thee. Throughout this whole epistle the apostle beseeches Timothy, in the most earnest manner, as a guardian of the faith, to preserve it without change. He every where condemns sects, heresies, and changes in faith. It would be well for the modern religionists, to inform us and themselves, why St. Paul is so particular in insisting upon union of faith, under pain of damnation, if it was the intention of Christ that men should differ on questions of religion. Let them tell us what St. Paul means, or else say plainly that they differ from the apostle’s religion, and have formed theirs upon a more liberal scale. (Haydock)