They profess that they know God; but in works they deny him, being abominable, and disobedient, and unto every good work reprobate.
All Commentaries on Titus 1:16 Go To Titus 1
The swine therefore is clean. Why then was it forbidden as unclean? It was not unclean by nature; for, all things are pure. Nothing is more unclean than a fish, inasmuch as it even feeds upon human flesh. But it was permitted and considered clean. Nothing is more unclean than a bird, for it eats worms; or than a stag, which is said to have its name from eating serpents. Yet all these were eaten. Why then was the swine forbidden, and many other things? Not because they were unclean, but to check excessive luxury. But had this been said, they would not have been persuaded; they were restrained therefore by the fear of uncleanness. For tell me, if we enquire nicely into these things, what is more unclean than wine; or than water, with which they mostly purified themselves? They touched not the dead, and yet they were cleansed by the dead, for the victim was dead, and with that they were cleansed. This therefore was a doctrine for children. In the composition of wine, does not dung form a part? For as the vine draws moisture from the earth, so does it from the dung that is thrown upon it. In short, if we wish to be very nice, everything is unclean, otherwise if we please not to be nice, nothing is unclean. Yet all things are pure. God made nothing unclean, for nothing is unclean, except sin only. For that reaches to the soul, and defiles it. Other uncleanness is human prejudice.
But unto them that are defiled and unbelieving is nothing pure; but even their mind and conscience is defiled.
For how can there be anything unclean among the pure? But he that has a weak soul makes everything unclean, and if there be set abroad a scrupulous enquiry into what is clean or unclean, he will touch nothing. For even these things are not clean, I speak of fish, and other things, according to their notions; (for their mind and conscience, he says, is defiled,) but all are impure. Yet Paul says not so; he turns the whole matter upon themselves. For nothing is unclean, he says, but themselves, their mind and their conscience; and nothing is more unclean than these; but an evil will is unclean.