As such, this passage seems to imply that Christians are now in the Kingdom of God. However, this clearly isn't the case, since 1 Corinthians 15:50 1 Corinthians 15:50Now this I say, brothers, that flesh and blood cannot inherit the kingdom of God; neither does corruption inherit incorruption.
American King James Version×tells us that "flesh and blood [physical bodies] cannot inherit the kingdom of God."
Part of the confusion here comes from the meaning of the word kingdom. In addition to meaning a literal kingdom, the Greek word basileia, translated "kingdom," denotes sovereignty and royal power (Vine's Complete Expository Dictionary of Old and New Testament Words, "Kingdom").
This passage in Colossians shows that God's sovereignty and power begin in the life of the Christian at conversion. The New International Version Study Bible explains that in this verse the word kingdom "does not here refer to a territory but to the authority, rule or sovereign power of a king. Here it means that the Christian is no longer under the dominion of evil (darkness) but under the benevolent rule of God's Son."
Virtually all other occurrences of basileia, when referring to the Kingdom of God, point to the literal dominion that Christ will establish at His return (Matthew 6:33 Matthew 6:33But seek you first the kingdom of God, and his righteousness; and all these things shall be added to you.
American King James Version×; Revelation 11:15 Revelation 11:15And the seventh angel sounded; and there were great voices in heaven, saying, The kingdoms of this world are become the kingdoms of our Lord, and of his Christ; and he shall reign for ever and ever.
American King James Version×). As "heirs of God" in training to inherit that future Kingdom (Romans 8:15-17 Romans 8:15-17  For you have not received the spirit of bondage again to fear; but you have received the Spirit of adoption, whereby we cry, Abba, Father.  The Spirit itself bears witness with our spirit, that we are the children of God:  And if children, then heirs; heirs of God, and joint-heirs with Christ; if so be that we suffer with him, that we may be also glorified together.
American King James Version×; Matthew 25:34 Matthew 25:34Then shall the King say to them on his right hand, Come, you blessed of my Father, inherit the kingdom prepared for you from the foundation of the world:
American King James Version×; Revelation 20:4-6 Revelation 20:4-6  And I saw thrones, and they sat on them, and judgment was given to them: and I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received his mark on their foreheads, or in their hands; and they lived and reigned with Christ a thousand years.  But the rest of the dead lived not again until the thousand years were finished. This is the first resurrection.  Blessed and holy is he that has part in the first resurrection: on such the second death has no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years.
American King James Version×), Christians are thus already subject to the sovereignty and authority of that Kingdom, although not yet residents of it.
Jesus Christ, ruler of the coming Kingdom, is the Lord and Master of Christians now (Philippians 2:9-11 Philippians 2:9-11  Why God also has highly exalted him, and given him a name which is above every name:
 That at the name of Jesus every knee should bow, of things in heaven, and things in earth, and things under the earth;
 And that every tongue should confess that Jesus Christ is Lord, to the glory of God the Father.
American King James Version×). God rules the lives of converted Christians who voluntarily obey Him and His laws. They submit themselves to God's basileia—His royal sovereignty and power. They individually are part of the Church, the Body of Christ, which God also rules. But the Church collectively looks to God's coming world rule when the basileia will be fully established.
The context leading up to Colossians 1:13 Colossians 1:13 Who has delivered us from the power of darkness, and has translated us into the kingdom of his dear Son:
American King James Version×also helps clarify the meaning. Colossians 1:9 Colossians 1:9 For this cause we also, since the day we heard it, do not cease to pray for you, and to desire that you might be filled with the knowledge of his will in all wisdom and spiritual understanding;
American King James Version×begins a description of points Paul and Timothy regularly included in their prayers. One of the blessings they were thankful for was that God had qualified them and the other members to receive the inheritance of the saints (Colossians 1:12 Colossians 1:12 Giving thanks to the Father, which has made us meet to be partakers of the inheritance of the saints in light:
American King James Version×). That inheritance, eternal life, does not come until Christ returns (1 Corinthians 15:50-52 1 Corinthians 15:50-52  Now this I say, brothers, that flesh and blood cannot inherit the kingdom of God; neither does corruption inherit incorruption.  Behold, I show you a mystery; We shall not all sleep, but we shall all be changed,  In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.
American King James Version×; Romans 8:17 Romans 8:17And if children, then heirs; heirs of God, and joint-heirs with Christ; if so be that we suffer with him, that we may be also glorified together.
American King James Version×). This is why the Bible refers to the saints as heirs of the Kingdom (James 2:5 James 2:5Listen, my beloved brothers, Has not God chosen the poor of this world rich in faith, and heirs of the kingdom which he has promised to them that love him?
American King James Version×).
Colossians 1:13 Colossians 1:13 Who has delivered us from the power of darkness, and has translated us into the kingdom of his dear Son:
American King James Version×continues this theme, adding that those qualified as heirs, those whose status had changed from nonheirs to heirs, were also "translated," or transferred, from the power of darkness to the Kingdom of God.
We, as modern-day saints, also exchange systems of government when we are converted. We now give our allegiance and obedience to the Kingdom of God, even though that Kingdom has not yet fully come.
In 2 Corinthians 5:20 2 Corinthians 5:20Now then we are ambassadors for Christ, as though God did beseech you by us: we pray you in Christ's stead, be you reconciled to God.
American King James Version×, Paul uses a different comparison to help us understand this, calling us "ambassadors." An ambassador is one who represents a kingdom or other government, but resides in a different land. Christians are thus ambassadors for God's Kingdom, representing His way of life in our current earthly situation and age in which we reside. We are not yet in the Kingdom of God.