The Ability to Gain the Victory over the Fallen Nature, the Flesh.
This article is gleaned from a current study in the book of Romans, focusing closely upon Romans 8:13-14.
The Christian has two natures abiding, 1) the old man that loves its own deceitful lusts and comforts and evils (Eph 4:22; Gal 5:19-21; 1 John 2:15-16), always warring against the things of Christ (Gal 5:17; Rom 7:23); and 2) the new man that “after God is created in righteousness and true holiness” (Eph 4:24; 2 Cor 5:17). The “old man,” is our old Adamic nature inherited from the first man, Adam, the father of us all. Adam sinned and brought death  into the world and made everyone born of an earthly father a sinner at conception. This nature is prideful and lustful and opposed to all righteousness and godliness (Rom 1:18). It is incapable of doing good (Rom 3:12). This nature cannot be reformed, nor eradicated until the grave or the rapture, whichever comes first. Mal Couch used to say “only the grave can cure a hunchback” and that is a true reflection of our old sinful nature.  But the “new man” cannot sin (1 John 3:9). But these two natures are continually warring against each other for controlling the direction of our hearts and our minds. Paul shows where the victory lies in Romans 8. It all has to do with our mindset. Where is our mind directed? After the flesh (old man) or after the Spirit (who always points us to Christ). Just as we thank God for Christ delivering us from the penalty of sin, so we thank God for giving us the victory over the present power of sin (7:25). We can and should let our minds dwell on things above, where Christ is (Rom 8:5; Col 3:2).
I have found much help in the following passages in getting the victory over sin in my life: Romans 8:13-14; Psa 141:8; 2 Cor 10:3-5; Heb 12:1-3. When confronted with temptations, we must recognize where the battle is going to take place. The desire to sin is always and only excited by temptations presented to our old man, Rom 7:17, 20, 21, 23, 25. Knowing this, let us see the instruction from Romans 8:13-14.
“For if ye live after the flesh, ye shall die: but if ye through the Spirit do mortify the deeds of the body, ye shall live. 14 For as many as are led by the Spirit of God, they are the sons of God.”
All that will result from living a life dedicated to fulfilling the desires of the old man is death. Death of relationships, testimonies, fruitfulness, etc. But if we through the Spirit do mortify the deeds of the body, our thoughts, our eyes, ears, tongues, feet, hands, etc. we shall live. This is another way of expressing Gal 2:20, but it is also a daily, ongoing work. We are to continually be mortifying the deeds of the body, so that the evil that is always present with us (7:21) does not excite the body to the wrong deeds. We are not to emasculate ourselves. But we can tell ourselves “No, flesh!” For that is where the temptations are targeted, to our flesh, our old man. Recognize it as contrary to the will of Christ and pre-empt it. Martin Luther said “You cannot keep the birds from flying over your head, but you can keep them from building a nest in your hair.” The flesh must be pre-empted and confronted.

The next verse I find helpful is Psa 141:8. I love it as the KJV translates it “But mine eyes are unto thee, oh God, the LORD; in thee is my trust, leave not my soul destitute.” There have been many times in my Christian life that my soul has been left destitute, because I got my eyes off of my Lord and Savior. As long as I keep my eyes upon the Lord, I will find the refuge to which I can flee for safety. There he will never leave my soul destitute, but full and satisfied and safe.
Once we have confronted the temptation, it is needful to set our focus elsewhere, upon the Lord Himself. The longer we let our mind or our eyes linger upon the temptation, the more likely our old man is to gain the upper hand and lead us into sin. Deny the flesh, look to the Lord! And look to His commandments.
Though 2 Cor 10:3-5 is talking about confronting doctrines that are contrary to Biblical Christianity, there is some indirect application that is mandatory for gaining the upper hand over the flesh’s dominance in our lives. Here is the passage,
“For though we walk in the flesh, we do not war after the flesh: 4 (For the weapons of our warfare are not carnal, but mighty through God to the pulling down of strong holds;) 5 Casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ;”
First, it is a warfare that cannot be waged in our own abilities and strengths. It is an ability that God provides through His Word and His Spirit, pointing us to Christ. The word mighty in verse 4 is from the Greek word DUNAMIS, often translated power. It is power, as in ability. Every imagination, every philosophy that is opposed to God is to be cast down. The word imaginations has to do with our fallen logic in thoughts and reasonings. We can often let our minds wander into vain imaginations, thinking on those things that are not necessarily true and supposing that they are. My mind has done that many a time and I can begin to build up a resentment based upon the vain imagining against someone else. And it is all based upon something that probably is not true at all! Again, indirect application, “No, flesh!” And finally the key point, “bringing into captivity every thought to the obedience of Christ.” Notice the contrast with Romans 7:23. If we fail to bring every thought into captivity of the obedience of Christ, then we will be brought into captivity of the law of sin (and death) because we will let the evil that is always present with us gain the upper hand and we will respond in a carnal manner, rather than in a Christ like manner.
We must recognize the target of temptations, guard against and deny the deceitful lusts of the old man, get our spiritual eyes back upon our Savior, and know His commands and obey His commands as regarding the thoughts that enter our minds. This is being “led by the Spirit” in regards to the temptations that would lead us into sin, and the “Do Not” commands of the New Testament. But we also are “led by the Spirit” in fulfilling the commands of Christ in regards to serving one another, loving others and sharing the truth of the gospel with the lost, and all of the other “Do” commands we find in the New Testament. “For as many as are led by the Spirit of God, they are the sons of God” Rom 8:14. Sons here is from HUIOS and has the idea of mature sons, ready for the responsibilities of carrying out the business for and on behalf of the Father. It is the same as “being filled with (controlled by) the Spirit” in Eph 5:18 and letting “the word of Christ dwell in you richly with all wisdom” in Col 3:16.
There was a fad in the 1990s that had young Christians wear bracelets with the letters WWJD on them. It stood for “What would Jesus do.” It was a good attitude to instill in Christians. The only better question to ask would be directly to the Lord “Jesus, “what would you have me to do?”  His Holy Spirit will remind us of the words of the Bible so that we can readily find the answer to that question. For that is His work, to remind us of what Christ said and did and to bear witness to us of our Savior and point us always to Christ Jesus our Lord. We must do this with every thought that crosses our mind.