Always Be at it!
Do you mortify? Do you make it your daily work? Do not take a day off from this work; always be killing sin or it will be killing you. We must strike it as an enemy until it ceases living. Sin is laboring to bring forth the deeds of the flesh. When sin lets us alone, we may let sin alone. Sin is active when it seems to be the most quiet, and its waters are often deep when they are calm. Sin is always acting, conceiving, seducing and tempting. There is not a day but sin foils or is foiled. There is no safety but in a constant warfare from sin's perplexing rebellion.
Do you mortify? Do you make it your daily work? Do not take a day off from this work; always be killing sin or it will be killing you. We must strike it as an enemy until it ceases living. Sin is laboring to bring forth the deeds of the flesh. When sin lets us alone, we may let sin alone. Sin is active when it seems to be the most quiet, and its waters are often deep when they are calm. Sin is always acting, conceiving, seducing and tempting. There is not a day but sin foils or is foiled. There is no safety but in a constant warfare from sin's perplexing rebellion.
Sin will not only be striving, acting, rebelling, troubling, and disquieting if not continually mortified, it will also bring forth great, cursed, scandalous, and soul-destroying sins (Gal.5:19-20). When sin rises to tempt, it always seeks to express itself in the extreme. Every unclean thought would be adultery if it could; every covetous desire would be oppression; and every thought of unbelief would be atheism.
It is like the grave that is never satisfied. Sin's advance blinds the soul from seeing its drift from God. The soul becomes indifferent to sin as it continues to grow. The growth of sin has no boundaries but the utter denial of God and opposition to him. Sin proceeds higher by degrees; it hardens the heart as it advances.
Mortification withers the root and strikes at the head of sin every hour. The best saints in the world are in danger of a fall if found negligent in this important duty. Negligence of this duty decays the inner man instead of renewing him. It is our duty to be "bringing holiness to completion in the fear of God" (2 Cor. 7:1), and every day to be growing in grace (I Pet. 2:2), and seeking to be renewed in the inner nature day by day (2 Cor. 4:16).
(From The Works of John Owen: volume six; published by Banner of Truth Trust: pages 9-14)