Even though we are redeemed, we still struggle with sin. But as Christians, we should be increasingly fighting sin and becoming more like Christ. Ephesians 4:1 calls believers to walk worthy of our calling. We are to walk "in balance" with the gospel that has saved us. In other words, the gospel that saves us, if it is genuine, is also transforming us. Simply put, as Christians, we should reflect the One we worship!
The term we use for our spiritual growth after our salvation is sanctification. While we are declared righteous at our justification when we are converted, the goal of the Christian life is to become in practice what we are in position. Theologians speak of mortification and vivification: dying to the old self and making alive the new human condition. We are to die to ourselves while we walk in the newness of spiritual life.
Some believe that sanctification is not important. However, you simply cannot read the Bible and come away with that impression. Others believe intellectual knowledge alone is sufficient for sanctification. But the truth is that we must increase in knowledge and obedience. It is possible to be theologically brilliant but not faithful to obey the will of God. That is not sanctification. The great pursuit for every true Christian is to deny ourselves and take up our cross daily (die to self), while we also follow Jesus in every way (daily obedience).
Our sanctification is a constant battle to embrace holiness while at the same time fighting sin.
Romans 8:7-13 -- For the mind that is set on the flesh is hostile to God, for it does not submit to God's law; indeed, it cannot. Those who are in the flesh cannot please God. You, however, are not in the flesh but in the Spirit, if in fact the Spirit of God dwells in you. Anyone who does not have the Spirit of Christ does not belong to him. But if Christ is in you, although the body is dead because of sin, the Spirit is life because of righteousness. If the Spirit of him who raised Jesus from the dead dwells in you, he who raised Christ Jesus from the dead will also give life to your mortal bodies through his Spirit who dwells in you. So then, brothers, we are debtors, not to the flesh, to 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.
Colossians 3:1-4 -- If then you have been raised with Christ, seek the things that are above, where Christ is, seated at the right hand of God. Set your minds on things that are above, not on things that are on earth. For you have died, and your life is hidden with Christ in God. When Christ who is your life appears, then you also will appear with him in glory.
Philippians 2:12-13 -- 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, for it is God who works in you, both to will and to work for his good pleasure.
Yes, the Spirit of God sanctifies us but not apart from our obedience. In other words, yes, the Spirit is teaching us, transforming us, and growing us. At the same time, we are called to obey and follow (to "work out your own salvation"). As the Spirit works within us, we are to be quick to confess sin, walk in obedience, and honor the Lord with our lives. And our sanctification impacts every part of who we are as human beings. No part of our lives is left unaffected.
It affects our mind (Colossians 3:10)
It affects our attitude (Ephesians 4:31)
It affects our will (Philippians 2:13)
It affects our bodies (Romans 12:1)
The words of 1 Thessalonians 5:23 sum up what this is all about as Scripture declares, "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.
As Christians, we have been justified. We belong to God as His Children. As His children, we will one day be glorified. But for today -- and the rest of our lives on this earth -- let us make our sanctification the great pursuit of our lives. Trust in the Lord who is always working in you, and let the knowledge of the Spirit's work give you motivation and focus to walk in a manner worthy of your calling!