Justification and sanctification are terms to describe two parts of the process of salvation. It is critically important to understand their relationship to each other and to the status of the one who wishes to be saved by the atoning death of Jesus Christ. What part does sanctification play in the saving process? Two different gospels arise from two answers to this question. Let us examine the inspired evidence regarding sanctification.
The most basic meaning of sanctification is "to set apart for a holy use." When God finished creating the earth and all life upon it, He set apart the seventh day as a memorial of His creative acts. God put His special blessing upon this day, because it was to be set apart for all time for the human race to use in a holy way.
The Sabbath was not set apart just as a holy day, but it was to be a sign or symbol that just as God sanctified the Sabbath, He sanctified His people. His people were also set apart for a holy use. It is very important to note right at the beginning that God does the sanctifying. He sanctified the Sabbath and He sanctifies us. It is currently popular to think that while God does the justifying, God and man together do the sanctifying. We must understand that in the process of salvation, it is God's work from beginning to end, both in justification and sanctification. Now we have a part to play in responding to God's saving work. We believe, we respond, we surrender, we cooperate. But these are only our responses to God's grace. None of these responses earn or merit our salvation. At the most, our responses give God the permission to do His justifying and sanctifying work in our lives.
When God instituted the sanctuary system for Israel, the first thing He did, before any ceremonies were carried out in the sanctuary, was to set apart the furniture and the priest for holy use. Before any sacrifices for sin were offered in the sanctuary, God sanctified the altar for its holy use. And it is important to note that God sanctified Aaron in exactly the same way as He sanctified the altar. It was God's work from beginning to end. From that point on, the sanctuary and the priests were set apart for holy use.
The person who is washed from sin, who has been cleansed by the blood of Jesus, who stands justified and pardoned in the sight of God, is also sanctified in that very act. When we are justified and washed, we are set apart for a holy use. God looks at us, not in our filthy garments of sin, but now clothed with the pure righteousness of Christ. We are declared to be sanctified, or set apart for holiness. Just as we are declared to be justified, or pardoned from our sins, we are declared to be sanctified. In this way the thief on the cross was both justified and sanctified, because he had been set apart for holiness. In passing, we might note that Paul places washing and sanctifying before justifying, perhaps to make the point that they are really all part of one saving process.
When Jesus spoke to Paul on the road to Damascus, He told Paul that his mission would be to bring the Gentiles to forgiveness of sins and salvation. If the Gentiles would turn from Satan to God, they would be called sanctified by faith in Christ (the same faith which would justify them). Just as forgiveness of sins is possible only by faith in Christ's life and death, so sanctification is possible only by the same faith in Christ. Both justification and sanctification are received by faith, because both are acts of God and flow totally from God's grace. And it is crucial to understand that both justification and sanctification are necessary prerequisites to salvation. The Bible does not teach that justification saves, while sanctification comes along later as the result of being saved.
Just as justification is declared by God at the moment of conversion, so sanctification is declared by God at the same moment. We are set apart for holiness, and God looks at us through the holy character of Jesus Christ. In this way we can have complete assurance of salvation. It is often said that this understanding of the gospel deprives us of assurance, but this is totally false. When the heart is surrendered and we wear the robe of Christ's righteousness, we have perfect peace and assurance, while we continue to grow in Christ.