Titus 1:15

15. Pure all things… pure Just so far as the heart is pure the eye is pure. The heart, under complete control of the law of purity, sees no effective incitement to lust in the external object. That control is the joint resultant of the divine law, the indwelling Spirit, and the firm will. Just so far as all concur, the world presents no objective temptation that wakes the sinful response from within.

Them that are defiled The slow-bellies of Titus 1:12. Their inward nature is tinder, that takes fire at every presented spark; and the sparks are flying in perpetual circles around it. Every hour of the day objects are occurring to awaken lust, gluttony, rapine. Such men frame to themselves a dim theory of life that nothing is pure, and that all virtue is sham. To them no woman is chaste, no man is honest. All apparently good people are hypocrites; and your only honest man is the free liver, who commits all rascality and makes no pretensions to a moral life. Nothing and nobody is pure, just because they themselves are defiled.

And unbelieving Without that faith which works by love and purifies the heart, as these gainsayers, and slow-bellies, and their subverts (Titus 1:11) were.

Their mind Their intellect, so that they think in accordance with systematic wrong, and believe that they believe it, in spite of an under-current of moral misgiving.

And conscience Their moral sense is abolished, (save the above under-current, which cannot be destroyed,) and a false conscience is constructed, by which wrong is seen by them to be their right.