It is the Spirit alone that can mortify sin; he is promised to do it, and all other means without him are empty and vain. How shall he, then, mortify sin that has not the Spirit? A man may easier see without eyes, speak without a tongue, than truly mortify one sin without the Spirit.
John OwenLet not that man think he makes any progress in holiness who walks not over the bellies of his lusts. He who doth not kill sin in this way takes no steps toward his journey's end.
John OwenI have known some good men who have been so addicted to their study, that they have thought the last day of the week sufficient to prepare for their ministry, though they employ all the rest of the week in other studies. But your business is to trade with your spiritual abilities. ... A man may preach a very good sermon, who is otherwise himself; but he will never make a good minister of Jesus Christ, whose mind and heart are not always in the work. Spiritual gifts will require continual ruminating on the things of the Gospel in our minds.
John Owen