How do we know that Christ is the source of all fullness?

The biblical affirmation that Christ is the source of all fullness is rooted in both Old and New Testament teachings. In Colossians 1:16, it is stated that by Him all things were created, reinforcing His preeminence over all creation. Additionally, His role as Mediator indicates that everything God requires of sinners is fully satisfied in Him. The phrase 'in Him you are complete' from Colossians 2:10 further supports this, illustrating that believers lack nothing in Jesus as He encompasses all elements of salvation, grace, and truth.