They profess that they know God - That is, the Jewish teachers particularly, who are referred to in Titus 1:14. All those persons were professors of religion, and claimed that they had a special knowledge of God.
But in works they deny him - Their conduct is such as to show that they have no real acquaintance with him.
Being abominable - In their conduct. The word here used - βδελυκτοὶ bdeluktoi - occurs nowhere else in the New Testament. It means that which is detestable, or to be held in abhorrence.
And disobedient, and unto every good work reprobate - Margin, “void of judgment.” On the word here used - ἀδοκίμος adokimos - see the Romans 1:28 note; 2 Corinthians 13:5 note. It means here that in reference to everything that was good, their conduct was such that it could not be approved, or deserved disapprobation. It was for this reason; from the character of the people of the island of Crete, and of those who claimed to be teachers there enforcing the obligation of the Mosaic law, that it was so important for Titus to exercise special care in introducing men into the ministry, and in completing the arrangements contemplated in the organization of the churches there. Yet is this character confined to them? Are there none now who profess that they know God, but in works deny him; whose conduct is such that it ought to be abhorred; who are disobedient to the plain commands of God, and whose character in respect to all that pertains to true piety is to be disapproved by the truly pious, and will be by God at the last day? Alas, taking the church at large, there are many such, and the fact that there are such persons is the grand hindrance to the triumphs of religion on the earth. “The way to heaven is blocked up by dead professors of religion.”