Paul uses theseterms to let the Colossians know that or rather tto remind them when they were in the world or did not know Christ or what He stood for that they were doing the things of the world and living the way of the world and when they heard the word of God and they accepted Christ they no longer operated in the world system because they had bee shown the way to God's marvelous light because Christ is the light of the world and through Him they are sons of God in Him ( Christ) we are kings and priest and we are all part of Christ. Because the Devil is of the world system, therefore Christ is of the Kindom system and if we are followers of Christ then we are of the Kingdom system. Therefore Kingdom system is constuited of Light, Love, Redemption and Forgaveness whereby the world system is of nothing but Darkness, Destruction and Death.