Sanctification is the synergestic work of God and man working together to make an inward reality an outward possibility. Justification is what saves us, it is the cornerstone by which our salvation stands or falls. It is because of justification that we are legally justified before God and because we are justified before God we can never be brought before the Judge again for being a sinner, if we were able to be placed before the Judge again for being a sinner and found guilty once again this would be double jeopardy and we know that in a court of law that is a just system a person cannot be found guilty twice of the same charge. It is because of this that a person cannot lose their salvation, if a person could lose their salvation the Lord would be an unrighteous Judge because of double jeopardy. Since we know that double jeopardy is unjust and that the Lord is a Just Judge that no one can be brought back before the Judge again for the same crime, being a sinner, the charge is being guilty of sinning which once found innocent of that crime we can never be brought before that judicial system again, because of double jeopardy. We are justified by faith and grace, the beautiful part of us being justified is that not only are justified never to go before the judicial system again, but we are imputed the righteousness of Chirst who knew no sin.
Romans 3:24 “being justified freely by His grace through the redemption that is in Christ Jesus,”
Romans 5:1-2 “Therefore, having been justified by faith, we have peace with God through our Lord Jesus Christ,2 through whom also we have access by faith into this grace in which we stand, and rejoice in hope of the glory of God.....16 And the free gift is not like the result of that one man's sin. For the judgment following one trespass brought condemnation, but the free gift following many trespasses brought justification.17 For if, because of one man's trespass, death reigned through that one man, much more will those who receive the abundance of grace and the free gift of righteousness reign in life through the one man Jesus Christ.”
Now being justified through faith and grace by which we stand, we receive the free gift of righteousness the righteousness of Chirst that knew no sin. We are now justified as if we knew no sin or to use that saying, "just as if I never sinned" in our born again state. Now the sanctification process is getting the outward man to be more like the inward man.
Now that our justification is settled, we can move on to sanctification, this is where Philippians 2:12-13 start working in our lives “Therefore, my beloved, as you have always obeyed, so now, not only as in my presence but much more in my absence, work out your own salvation with fear and trembling,13 for it is God who works in you, both to will and to work for his good pleasure.”
Here is where many get justification mixed up with sanctification, by thinking that a person can lose their salvation because of sin in thier lives. Sin will always be in our lives because we are sinners, here's the part that interests me for those that believe someone can lose their salvation and that is how they view sin. Since we all sin and always sin, how can anyone keep their salvation? They can't if the second you sin you lose it, not one would/could ever stay saved, how do we know this I John 1:7-10
“But if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus his Son cleanses us from all sin.8 If we say we have no sin, we deceive ourselves, and the truth is not in us.9 If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.10 If we say we have not sinned, we make him a liar, and his word is not in us.”
You say you have no sin so you can continue in your salvation, the Bible says you are a liar and the truth is not in you and you deceive yourself. Thank God for justification and Christ's righteousness so that we can work with God on our salvation process knewn as sanctification trying to get that sin that is in us, out. Hey wait a minute I thought we have Christ's righteousness now and are sinless? Yes we do, in our spirit we are born again and in our spirit we are sinless, but in our flesh we are sinful. Romans 7:5-6, 14-20
“For while we were living in the flesh, our sinful passions, aroused by the law, were at work in our members to bear fruit for death.6 But now we are released from the law, having died to that which held us captive, so that we serve in the new way of the Spirit and not in the old way of the written code......14 For we know that the law is spiritual, but I am of the flesh, sold under sin.15 For I do not understand my own actions. For I do not do what I want, but I do the very thing I hate.16 Now if I do what I do not want, I agree with the law, that it is good.17 So now it is no longer I who do it, but sin that dwells within me.18 For I know that nothing good dwells in me, that is, in my flesh. For I have the desire to do what is right, but not the ability to carry it out.19 For I do not do the good I want, but the evil I do not want is what I keep on doing.20 Now if I do what I do not want, it is no longer I who do it, but sin that dwells within me......25 Thanks be to God through Jesus Christ our Lord! So then, I myself serve the law of God with my mind, but with my flesh I serve the law of sin.”
So we see that our flesh serves the law of sin in it's sinful ways, but with our mind we serve the law of God this is the sanctification process or battle that wage with-in us Galathians 5:16-17 “But I say, walk by the Spirit, and you will not gratify the desires of the flesh.17 For the desires of the flesh are against the Spirit, and the desires of the Spirit are against the flesh, for these are opposed to each other, to keep you from doing the things you want to do.”
So we battle the spirit that is born again to sinless perfection and the flesh ful of sinful desires and that sinful flesh influances the mind at time and cause it to lust, but as we use the mind to serve the law of God we help bring the flesh and your whole being into sanctification, I Thessalonians 5:23 “Now may the God of peace himself sanctify you completely, and may your whole spirit and soul and body be kept blameless at the coming of our Lord Jesus Christ.”
Sanctification is as Paul says in Philippians it is the working out of our salvation with reverence and godly respect for the Lord and the sacrifice that He made for our justification, that we can work with Him in our santification process honoring and respecting Him in the process, thank you Jesus.