What does sanctification by the Spirit mean?

Sanctification by the Spirit is a crucial aspect of the Christian faith, indicating the transformative work of the Holy Spirit in the life of a believer. In 2 Thessalonians 2:13, Paul links sanctification with salvation, showing that it is through the Spirit that believers are enabled to grow in holiness and obedience to God's commands. This work of sanctification is not merely external behavior modification; rather, it is an inward change that produces a desire for righteousness and a distaste for sin. Such transformative work assures believers of their election and is evidence of their relationship with God.