It is God’s will that you should be sanctified. 1 Thessalonians 4:3 NIV
A helpful way to understand sanctification is by contrasting it with justification—twin blessings that God gives to every Christian in this life.
Justification is about forgiveness so that you may come to God.
Sanctification is about holiness so that you may become like God.
In justification, God calls us to believe.
In sanctification, God calls us to watch, fight, and pray.
Justification is Christ’s hidden work. You cannot tell if a person is forgiven. It is the gift of God given in secret as a person comes to faith in Christ.
Sanctification is Christ’s visible work. You can tell if a person is becoming more like Jesus. By their fruits you shall know them. A good tree produces good fruit.
Justification and sanctification are quite distinct from one another, and we run into difficulties when we get them confused.
Some Christians think that their acceptance with God (justification) depends on the degree of success they experience in their battle with sin. But if that’s what you think, you will never enjoy peace with God or be confident in His love.
Other Christians have grasped that salvation is about forgiveness for the past and heaven for the future, but they have never grasped that salvation is also about the power of Christ in your life now (sanctification), and so they never change.
It is important to grasp that justification and sanctification are different blessings, and they should not be confused, but they are always found together and they should not be separated.
Which do you struggle with more: Feeling accepted by God? Or experiencing the power to change in the Christian life?