The choicest believers, who are assuredly freed from the condemning power of sin, ought yet to make it their business all their days to mortify the indwelling power of sin.
Mortification from a self-strength, carried on by ways of self-invention, unto the end of a self-righteousness, is the soul and substance of all false religion in the world.
The vigour, and power, and comfort of our spiritual life depends on the mortification of the deeds of the flesh.
Do you mortify; do you make it your daily work; be always at it whilst you live; cease not a day from this work; be killing sin or it will be killing you. Your being dead with Christ virtually, your being quickened with him, will not excuse you from this work.
Who can say that he had ever any thing to do with God or for God, that indwelling sin had not a hand in the corrupting of what he did? And this trade will it drive more or less all our days. If, then, sin will be always acting, if we be not always mortifying, we are lost creatures. He that stands still and suffers his enemies to double blows upon him without resistance, will undoubtedly be conquered in the issue. If sin be subtle, watchful, strong, and always at work in the business of killing our souls, and we be slothful, negligent, foolish, in proceeding to the ruin thereof, can we expect a comfortable event? There is not a day but sin foils or is foiled, prevails or is prevailed on; and it will be so whilst we live in this world.
There is not the best saint in the world but, if he should give over this duty, would fall into as many cursed sins as ever any did of his kind.
The contest is for our lives and souls. Not to be daily employing the Spirit and new nature for the mortifying of sin, is to neglect that excellent succour which God hath given us against our greatest enemy. If we neglect to make use of what we have received, God may justly hold his hand from giving us more. His graces, as well as his gifts, are bestowed on us to use, exercise, and trade with. Not to be daily mortifying sin, is to sin against the goodness, kindness, wisdom, grace, and love of God, who hath furnished us with a principle of doing it.
Where sin, through the neglect of mortification, gets a considerable victory, it breaks the bones of the soul, Ps. xxxi. 10, li. 8, and makes a man weak, sick, and ready to die, Ps. xxxviii. 3-5, so that he cannot look up, Ps. xl. 12, Isa. xxxiii. 24; and when poor creatures will take blow after blow, wound after wound, foil after foil, and never rouse up themselves to a vigorous opposition, can they expect any thing but to be hardened through the deceitfulness of sin, and that their souls should bleed to death? 2 John 8. Indeed, it is a sad thing to consider the fearful issues of this neglect, which lie under our eyes every day.
Let 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 towards his journey’s end.
The root of an unmortified course is the digestion of sin without bitterness in the heart. When a man hath confirmed his imagination to such an apprehension of grace and mercy as to be able, without bitterness, to swallow and digest daily sins, that man is at the very brink of turning the grace of God into lasciviousness, and being hardened by the deceitfulness of sin. Neither is there a greater evidence of a false and rotten heart in the world than to drive such a trade.
– From Volume 6 of Owen’s Works