Why is it significant that salvation is both justification and sanctification?

In sovereign grace theology, the significance of salvation encompassing both justification and sanctification is foundational. Justification declares believers righteous before God, based entirely on Christ’s work, not on their merit. This legal standing before God provides peace and assurance of eternal life. On the other hand, sanctification represents the ongoing work of the Holy Spirit in a believer’s life, empowering them to live according to God’s will. Together, these elements reveal the holistic nature of salvation, where believers are freed from the penalty of sin and progressively freed from sin's power, ultimately leading them toward conformity to the image of Christ.