Justification and sanctification are not the same. Justification happens outside of us; sanctification takes place within us. One is about having righteousness credited to us, while the other involves righteousness being infused in us. Justification is a one-time event; sanctification is a gradual process. One person may be more sanctified than another, but no one can be more justified. Grace might vary among individuals, but justification remains equal.
The perfection in our justification lies in Christ’s righteousness. However, our sanctification is a work in progress, marked by imperfections and the flaws of God’s children. Our virtues are intertwined with sin, and our actions are often tainted. So, it is clear that justification and sanctification differ. But even with these distinctions, they are never disconnected.
When God pardons and justifies a sinner, He also sanctifies them. As 1 John 5:6 states, “This is He who came by water and blood, even Jesus Christ.” Here, Christ signifies forgiveness through His blood and sanctification through water. Let no man say he is pardoned who is not growing in holiness.
I emphasize this point against those who boast about their sins being forgiven and their connection to Christ while remaining unchanged and immersed in serious transgressions. Where there is forgiveness, there is purification. Every person God forgives, He transforms. No one should assert their sins are forgiven without sensing an ongoing work of holiness within. As Ezekiel 36:27 declares, “I will place My Spirit within you and cause you to follow My statutes and carefully observe My ordinances.”
-Thomas Watson (Updated for Today’s Reader)
The Fight of Faith 