How do we know that our sanctification is God's work?

Scripture, such as Ephesians 1:4 and Hebrews 10:10, reminds us that sanctification is God's divine initiative in the life of a believer. From eternity, God predestined us to be holy, and at the cross, Christ sanctified His people through His one offering. This means our holiness is not of our own doing; it is entirely God's grace at work in us by His Spirit. Our sanctification, therefore, is a gift from God, emphasizing His sovereign grace in bringing us from spiritual death to life, enabling us to grow in righteousness.