What does the Bible teach about sanctification?

Sanctification, according to Reformed theology, is the process by which believers are made holy through the work of the Holy Spirit in them. As clearly delineated in Galatians 3, sanctification is not achieved through adherence to the law but through faith in Christ. Paul asserts that once we begin in the Spirit, we cannot complete our growth in holiness through the flesh (Galatians 3:3). Sanctification is progressive and rooted in the knowledge and understanding of Christ’s grace and redemptive work. As believers hear and believe in the truth of the gospel, they are increasingly conformed to Christ’s image. This transformation is continually fueled by hearing His word, which reinforces that our identity is found in Christ, making us increasingly like Him in character and behavior.