How do we know that Christ's fullness is in us?

The assurance that Christ's fullness is in believers comes from the clear teaching of Scripture. John 17:20-23 emphasizes that Jesus prayed not only for His immediate disciples but also for all who would believe in Him through their message. This indicates a universal truth that the fullness of God, through Christ, is imparted to all who truly believe. Colossians 1:27 states that Christ in you is the hope of glory, affirming that His presence within believers is assured by faith. Thus, the fullness of Christ is a transformative reality for every believer.