Those who belong to Christ were already killed with Him and it makes no sense to try to save what God has already condemned, this is the flesh, but we must put into practice the work of the cross in us.
If the Spirit of God dwells in us, it will also vivify our bodies by his Spirit, so we are debtors "because you, brothers, were called to liberty; only do not use liberty as an occasion for the flesh, but serve each other out of love "Galatians 5:13.
We were called to freedom in a world that makes liberty a life of debauchery, and even many of those we call Christians continue to fight in the flesh against those desires that lead them to live lives of slaves of sin.
Because those who believe in freedom to show that they can do everything, that there are no limits to the way of life they have, that they believe they are free because they are open-minded when in reality their lives are a transgression of the laws, authorities, everything that goes against their supposed freedom, and is why they commit aberrations against their own lives, making themselves slaves to the sinful desires of their flesh.
Let's read the Word of God in Hebrews 12: 7-15
"If you endure discipline, God treats you like children; because what son is he whom the father does not discipline? But if you are left without discipline, of which all have been participants, then you are bastards, and not children. On the other hand, we had our earthly parents who disciplined us, and we venerated them. Why will we not obey the Father of spirits much better, and live? And those, certainly for a few days they disciplined us as they pleased, but this one for what is profitable for us, so that we can participate in their holiness. It is true that no discipline at present seems to be cause of joy, but of sadness; but afterwards it gives a peaceful fruit of justice to those who have been exercised in it. Therefore, raise your hands and knees paralyzed; and make straight paths for your feet, so that I take it not to get out of the way, but to be healed. Follow peace with everyone, and holiness, without which no one will see the Lord. Take heed, lest anyone fail to attain the grace of God; that some root of bitterness springing up bothers you, and by it many are defiled. "
Humanity was created good and perfect because God is perfect, but when Adam and Eve sinned their nature was corrupted, and that sinful nature passed on to their offspring; so that both the physical and spiritual nature were good, but were negatively affected by sin and the end result is a nature that is called "the flesh," which opposes God and seeks sinful gratification, making it impossible for the natural man to please or serve God.
Paul states in Romans 7: 14-24 that there was something "in the members" that he calls "my flesh" that brings difficulty in his Christian life and makes him a prisoner of sin, and Luther says that Paul speaks there of the whole man, body and soul, reason and all its faculties, because everything that is in it longs for and strives for the flesh, which is to say that their affections and desires go against God in all areas of life.
We could classify the works of men into two large groups: The works of faith, and the works of the flesh, where the works of faith are in obedience to the Word of God, that is, by faith, and the end is eternal life; while the works of the flesh, are in obedience to our own lusts and are executed believing that what we do is what suits us and the end is death.
In practice, what I am saying is that if we listen to the voice of the Lord who speaks to our heart and we obey Him, we are being guided by His Holy Spirit and we die the works of the flesh in that act by not listening or obeying the meat.
This is why many come to church and leave their great sins, and change their way of speaking, instead of saying luck they say God bless you, but after some time they begin to fall back on sins they had left behind, or because they did not they like something and they think they are good, feeling frustrated they fall down, and they move away from the congregation.
There are also those who think that fasting is to move the hand of God on our behalf in the sense that it gives us things we desire, and they seek God for that alone, but fasting is for two fundamental things, approaching God having a Personal encounter in the Spirit, and dying to the flesh and our desires, these have to be the main goals of our Christian fasts.
There is no point in believing in Jesus Christ without believing that his Spirit helps us to overcome the works of our flesh, because if we do not believe it, we can not believe that it has the power to vivify our mortal bodies and raise us from the dead; and if we do not believe it, we should remember that the promises are reached by faith.
Those who live according to the flesh, and who do not want to change or repent of their sinful behavior will experience separation from God in this life, because "... what fruit did you have from those things that you are now ashamed of? For the end of them is death "Romans 6:21," Do not be deceived; God can not be mocked: for whatever a man sows, that will also reap. For he that soweth to his flesh shall of the flesh reap corruption; But he who sows to the Spirit will reap eternal life from the Spirit "Galatians 6: 7-8.
They say: "Not with an army, nor with strength, but with my Spirit, says the LORD of hosts" Zechariah 4: 6 in spiritual warfare, and the truth is that to overcome the flesh we can only do it with His Holy Spirit .
They want the Glory of God, but if the glory of God were to come down they would not bear it; To speak of holiness is a message that does not please and they call it legalism, religiosity, but the Bible says that without holiness no one will see God.
Many desire the outpouring of the Holy Spirit, but they are not ready because in their lives there is still flesh, that is why "no one puts new wine into old wineskins; otherwise, the new wine breaks the wineskins, and the wine is poured out, and the wineskins are lost; but new wine must be put into new wineskins "Mark 2:22; perhaps they took out the biggest sins, but there are still lies, deceptions, envies, jealousies, complaints, divisions, gossip, anger, rivalry, or drunkenness.
But "you, brothers, were called to liberty; only do not use freedom as an occasion for the flesh "Galatians 5:13, we were called to freedom in a world that makes liberty a life of debauchery that leads them to live as slaves to the sinful desires of their flesh.
So however much we draw out all that we consider sinful, but we do not take the root, which is the desire to do, or see, or touch, or consume, or in general the disordered desire or as the Bible calls concupiscence If we do not extirpate it by dying to the flesh with fasting, prayer, and action, it is in vain that we try to grow spiritually.
To overcome the flesh we only do it with his Holy Spirit, for "if the Spirit of him who raised Jesus from the dead dwells in you, he who raised Christ Jesus from the dead will also vivify your mortal bodies by his Spirit who dwells in you. So, brothers, we are debtors, not to the flesh, so that we live according to the flesh; for if you live according to the flesh, you will die; But if by the Spirit you put to death the deeds of the body, you will live "Romans 8: 11-13.
That is to say, we are faced with a condition, a condition, because if through the Holy Spirit we make the works of the flesh die, we will live; but if we live according to the flesh, we will die, and we are talking about Christians who already have the Holy Spirit, who have been born again, that is, the warning is for believers and not for unbelievers.
And it also tells us that it is not that the Spirit will do it alone, but that it is we who must do it through the Holy Spirit, since that Spirit had the power to raise Jesus from the dead and has the power to make our works die of the flesh, so we must use it to make the works of the flesh die since otherwise we will die.
Obeying the flesh always results in disobeying the law of God, but the Lord gives us a process to overcome the flesh and reestablish the right relationship with God, and for this, the first thing is to walk in honesty, recognizing the sinful behavior before God, for "if we say that we have no sin, we deceive ourselves, and the truth is not in us. If we say that we have not sinned, we make him a liar, and his word is not in us "1 John 1: 8,10.
Then we must walk in the Spirit, which is to keep Christ as savior and receive the Holy Spirit to live correctly before God and not obey the desires of the flesh, assuming like Paul that "with Christ I am crucified together, and I no longer live , but Christ lives in me; and what I now live in the flesh, I live in the faith of the Son of God, who loved me and gave himself for me "Galatians 2:20.
And the last step is when the flesh goes hungry for its desires to finally die, understanding that when a person is born again by the Spirit he still has the old nature with his desires battling with the new nature and desires that come from the Spirit, therefore, "put to death, therefore, the earthly in you: fornication, impurity, disordered passions, evil desires and greed, which is idolatry; things for which the wrath of God comes upon the children of disobedience "Colossians 3: 5-6.