Albert Barnes Commentary Titus 1:9

"holding to the faithful word which is according to the teaching, that he may be able to exhort in the sound doctrine, and to convict the gainsayers." — Titus 1:9 (ASV)

Holding fast the faithful word. That is, the true doctrines of the gospel. This means that he is to hold this firmly, in opposition to anyone who would wrest it away, and in opposition to all false teachers and all systems of false philosophy. He must be a man who is firm in his belief of the doctrines of the Christian faith, and one who can be relied on to maintain and defend those doctrines in all circumstances. (Compare to 2 Thessalonians 2:15).

As he hath been taught. The marginal reading is in teaching; the Greek, "according to the teaching." The sense is, according to that doctrine as taught by the inspired teachers of religion. It does not mean as he had individually been taught; rather, he was to hold the faith as it was delivered by those whom the Savior had appointed to make it known to mankind. The phrase, "the doctrine" or "the teaching," had a kind of technical meaning, denoting the gospel as that which had been communicated to mankind, not by human reason, but by teaching.

That he may be able by sound doctrine. By sound teaching or instruction. (See 1 Timothy 1:10; 1 Timothy 4:16).

He was not to dictate or to denounce; but to seek to convince by the statement of the truth. (See 2 Timothy 2:25).

Both to exhort and to convince. This means to persuade them, or to bring them over to your views by kind exhortation and by instruction that will convince. The former method is to be used when people know the truth but need encouragement to follow it; the latter, when they are ignorant or are opposed to it. Both exhortation and argument are to be used by ministers of religion.

The gainsayers. Opposers. Literally, those who speak against; that is, against the truth. .