Many Christians seem to think that salvation means (only) getting our sins forgiven and going to heaven. The Bible points out that there are three parts to salvation -- justification, sanctification and glorification. When we come to God repenting from our sins and receive forgiveness for our sins because of Jesus' death in our place, God justifies us. In simple terms, He accepts us as righteous in His sight. But then starts the lifelong process of sanctification, which involves transforming us from our old sinful ways to the character of Jesus. The third part of salvation is glorification, which means God giving us a new sinless body when we go to be with Him in eternity.
Justification gives us a confidence before God that there is no more any condemnation for us from God (Ro.8:1), God's wrath has been taken away (1Th.5:9), we can constantly be in the presence of God without fear (He.10:19-22), etc. These things give us boldness before God, especially when doubts and fears trouble us. When we know that we are God's children and He is with us and for us, we even have boldness to face trouble from people and situations on this earth (Ro.8:31). We need this kind of assurance and boldness if we are to survive our journey through this world.
To be sanctified means to be set apart for God. In one sense God has sanctified us (set us apart) for Himself (1Co.1:2), but on the other hand we are to sanctify ourselves to God (1Pe.3:15;Jn.17:19). It is when we deny ourselves our sinful desires and present ourselves as holy towards God that we get sanctified (Ro.6:19). Many people feel some kind of a contradiction when they have to recognise and deal with big and small sins in their lives, because that makes them feel as if they are coming away from justification! Some people say that when God has promised not to remember our sins any more (He.8:12), we should not be thinking about sin ourselves. Some other people feel very insecure when they look at the actual presence of sin in their lives because they fear they are denying God's grace over their lives. As a result, many people keep away from any mention of cleansing themselves (2Co.7:1), and then they do not experience sanctification.
The fact is that we have to learn to hold both justification and sanctification together in our lives. On one side we need to be without doubt that our sins have been completely forgiven and that God has accepted us without condition. Without letting go of this assurance, we must know that God wants to set us free from actual sinning in our practical lives too (1Jn.2:1,2). God knows we might fall into sin again after we have been justified, and therefore He has made the provision of confessing our sins and receiving forgiveness (1Jn.1:9). Justification is about God accepting us unconditionally, and sanctification is something we need to cooperate in by dealing with sin, without losing the sense of acceptance by God because of awareness of sin.