To the pure all things are pure, but to those who are defiled and unbelieving nothing is pure; but even their mind and conscience are defiled.—Titus 1:15
But when a conscience has become seared, when a man has played with the fire and burned his conscience and calloused it until he can handle the hot iron of sin without shrinking, there is no longer any safety for him.
Paul wrote in his epistle about those to whom nothing is pure any longer, "but even their mind and conscience is defiled."
Here Paul speaks of an inward corruption, revealed in impure thoughts and soiled language. I am just as afraid of people with soiled tongues as I am of those with a communicable disease.
Actually, a foul tongue is evidence of a deeper spiritual disease and Paul goes on to tell us that those with defiled consciences become reprobates, something just washed up on the shore, a moral shipwreck. Echoes from Eden, 64-65.
"Oh Lord, deliver me from that 'inward corruption.' Guard my mind and my tongue; convict me of any carelessness or straying. Keep my conscience alive and active. Lord, I really don't want to end up a dirty old man, 'washed up on the shore, a moral shipwreck.' Amen."