Therefore, since we have been justified by faith, we have peace with God through our Lord Jesus Christ.
— Romans 5:1
One of my seminary professors said, “Gentlemen, justification and sanctification must always be distinguished, but they can never be separated.” There is no man who is justified, pardoned by God, who is not in the process of being sanctified. If you are not being made holy, you are not justified. You are not saved. You are not a Christian and you are not going to Heaven.
Justification is an act; it happens instantaneously the moment we trust in Christ. It is perfect. It is complete. It is forever. Fifty years later, we are no more justified than we are in the first moment after we trust in Christ. The perfect righteousness of Jesus Christ never changes. It is finished. It is complete. It is done.
Justification deals with the guilt we have incurred because of our sin. It is a judicial, legal term. It is something a judge does. Sanctification is the work of a physician cleansing us from the corruption in our life.
It has been said that justification by faith alone is the article of a standing or falling church, of a standing or falling nation, of a standing or falling soul. Sanctification is the lifelong process of becoming more like Christ.