What does the Bible say about the assurance of grace?

The assurance of grace is rooted in the belief that God, who began a good work in us, will carry it on to completion until the day of Christ. This assurance is not based on human ability or perseverance, but on the unchanging purpose and faithfulness of God. Philippians 1:6 states this confidence clearly: 'He who began a good work in you will carry it on to completion.' Therefore, those truly regenerated by God's grace can be assured of their salvation, as it depends solely on God's continued work and not on their fluctuating will or effort.