13 He has delivered us from the domain of darkness and transferred us to the kingdom of his beloved Son, 14 in whom we have redemption, the forgiveness of sins. 
The Father has “qualified” believers to be adopted as children of God. He qualified believers by making them worthy. Verses 13-14 explain what it is that God did to make Christians worthy. In one motion, God has moved those who trust in Him from darkness to light in Jesus Christ.
People need rescue. Every individual is guilty of sin against a holy and magnificent King, who has every right to destroy all of humanity. Mankind has rejected God’s authority and determined to find righteousness on their own. In doing so, humanity has embraced the darkness and consciously rejected the Creator. The Bible articulates this reality using terms such as “sons of disobedience,” “children of slavery,” “accursed children,” and “children of the devil”(Ephesians 5:6, Galatians 4:31, 2 Peter 2:14, and 1 John 3:10). God has, first, rescued believers from the “domain of darkness” (v.13).
The “domain of darkness.” Before trusting in Christ all of humanity is under the rule of darkness. Darkness floods the soul of man making it impossible to discern between good and evil. On the rare occasion that a person does achieves some sort of altruistic motives, the darkness that blinds that person will inevitably destroy any positive work that one can muster. People are so blinded that they will not live up to the righteous requirements of a holy and perfect God. Further, this world is dark. Darkness has a level of dictatorship over the world in which humanity walks. This is what Paul means when he asserts that “the days are evil” and that the “natural man does not accept the things of God” (Eph. 5:16 and 1 Cor. 2:14). Darkness has such tyrannical control over the minds of people that there is an overwhelming unwillingness to pursue righteousness. But hope remains, God, the Father has rescued those who trust in Jesus from the control and authority of darkness. The power of darkness to blind the eyes of man has been overcome. The authority of sin in the life of a believer has been defeated because of Jesus. No longer is a believer subject to the dominion of evil. Now a believer is a child of the light and lives with the freedom to reject sin.
The believer’s freedom is secured by their citizenship. While darkness reigned over the unbeliever, the believer now is secure in the kingdom of Jesus. In contrast to the slavery of darkness, the kingdom of Jesus Christ offers freedom. Freedom to reject sin and pursue holiness. While in darkness, humanity is incapable and unwilling to reject sin. The nature of man is so bent towards darkness that righteousness seems utterly absurd. Yet, once transferred to the citizenship of heaven, the believer is empowered to stand against sin and pursue holiness. The worthy Christian life is made possible by the destruction of sins power and the transfer of allegiance.
To be a citizen of Jesus’ kingdom is to live in stark contrast to darkness. “God is light, and in him is no darkness at all” (1 John 1:5). Light exposes people and places on display the truth of character. Darkness hides the truth and allows wickedness to go unchecked. Light declares and embraces the disparity between God’s holiness and man’s unrighteousness. Darkness attempts to deny such disparate conditions. Light reveals both the need of man and the love of God. Darkness deceives unrighteous men into believing that they are righteous and have no need of God’s love. The Kingdom of Jesus Christ is the Kingdom of light.
Jesus serves as the atoning sacrifice for the sins of those who believe. He has redeemed His saints and has forgiven their sins. All who trust in Jesus are forgiven and redeemed. All who trust in Jesus can stand before God and know His love and call Him Father (c.f. John 20:17). Before Christ, humanity views God as an enemy while resting in the false comfort of darkness. After Christ, the darkness is exposed and driven away to reveal the beauty of God’s love for His own and the nature of a believer is changed in view of His holiness.