Colossians 1:19-20
19 For it pleased the Father that in him should all fulness dwell; 20 And, having made peace through the blood of his cross, by him to reconcile all things unto himself; by him, I say, whether they be things in earth, or things in heaven.
It is vitally important to note two words in the sentence above if we are going to understand what is being said, "In Him." In verse 19 we are told that it is in him that all fulness dwells and even the statements made in verse 20 are only true, of Him and those who are "In Him." The first idea that must be dealt with is the false doctrine of "universalism;" The idea that everybody will be reconciled to God through the atonement of Christ, even those who never believe in him. This is not what Paul is saying here or in other places, repentance and faith in Jesus Christ were preached as a prerequisite to salvation[Acts 20:21], and all those who never have trusted, never will be saved at any point.
Peace through his blood is "In Him." Reconciliation is "In Him." In Ephesians 1:10 He says: "That in the dispensation of the fulness of times he might gather together in one all things in Christ, both which are in heaven, and which are on earth; even in him:" Notice again the phrase at the end of this verse "In Him" and also he says he will "gather together in one all things in Christ." Keywords, "In Christ. The reconciliation of all things in heaven and earth is only true of Him and those who are in him.
The other verses of scripture that are in the same line as verse 20 is Phillipians 2:10-11 "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."
Here the things in heaven and earth are mentioned but even the things under the earth! The verses here say they should bow but Romans 14:11 says they shall and in Revelation 5:13-14 every creature in earth, heaven, and under the earth are confessing to him who sits on the throne. I believe the reconciliation spoken of in verse 20 of our study is one, reserved for those in Christ. Two, speaks of the fullness of Christ, that is completeness and sufficiency that is in Him, how that all things have been completed in Him and all things are "Reconciled" or made right. There is nothing left that needs to be done, all wrongs have been righted, all requirements have been met and he has satisfied God completely with his life, death, resurrection, and work of salvation. Nothing in heaven needs fixing for him to be Lord, nothing in the earth that needs to be done, and nothing under the earth. He is the fulness of all things and if we are in him then we are reconciled and there is nothing and no one who can lay any charge to us, not men, not principalities, not powers all things have been reconciled in Christ, the accounts have been reconciled and there is no one anywhere who can say this area or that area was not reconciled. It rings with the same tune as Col 2:10, "And ye are complete in him, which is the head of all principality and power."
Then keeping in mind the reason for Paul writing this letter to the Colossians, dealing with the false teaching of Gnosticism, the belief that Christ was an important figure in being reconciled to God, but not God himself and not the preeminent figure in reconciliation to God. This verse tells us that it is in Him that everything is made right, he has filled in all the gaps, and there is nothing and no one anywhere that can bring any accusation of his not having made all things right. The earth will bow to Christ, the heavens will bow to Christ, and even things under the earth will bow to Christ. They may accuse, deride, and abuse him now but one day in the not-so-distant future they will bow and confess that he is the Christ and he is the Creator and did make all things new. Sadly, it will be too late for those who never bowed the knee while grace was being extended. Like those in the days of Noah, grace was extended through His Spirit striving with them and the preacher of righteousness preaching to them. Then the period of God's grace was over and as the rains of God's judgment fell they finally believed but when it was too late. God reconciled the world back to himself through his purging judgment but the only ones who made it into God's new World were those who were in the Arc of God's salvation.
I'm so glad that I bowed the knee to Jesus in repentance and faith years ago and have been redeemed, forgiven, and reconciled. No one on earth can bring a railing accusation against Jesus or all those that are in Him. There is nothing in heaven that can bring an accusation against him or those in him, there is nothing under the earth that can bring any accusation against him or those in him. He has reconciled all things, he has filled all things, he is the fulness of all things. What a peace to know that my Lord has fixed it all! I'll close with some verses of scripture that I believe summarizes this thought very well.
Romans 8:34 Who is he that condemneth? It is Christ that died, yea rather, that is risen again, who is even at the right hand of God, who also maketh intercession for us.
Romans 8:38 For I am persuaded, that neither death, nor life, nor angels, nor principalities, nor powers, nor things present, nor things to come, 39 Nor height, nor depth, nor any other creature, shall be able to separate us from the love of God, which is in Christ Jesus our Lord.