Reconciliation of all things God unveiled to us through apostle Paul  His plan...

Colossians 1:20, NASB
to reconcile all things to Himself, having made peace through the blood of His cross; through Him, I say, whether things on earth or things in heaven.&quot;

With what &quot;things&quot; did God reconcile in heaven through the blood of His cross?
At the very least, all of creation will be &quot;reconciled&quot; - ie, made right again - at Christ's second coming:

&quot;For the creation was subjected to futility, not willingly, but because of Him who subjected it, in hope that the creation itself also will be set free from its slavery to corruption into the freedom of the glory of the children of God. For we know that the whole creation groans and suffers the pains of childbirth together until now.&quot; {Romans 8:20-22}

and

&quot;But according to His promise we are looking for new heavens and a new earth, in which righteousness dwells.&quot; {2 Peter 3:13}

and

&quot;Then I saw a new heaven and a new earth; for the first heaven and the first earth passed away, and there is no longer any sea.&quot; {Revelation 21:1}

More importantly, though, is the context in which Colossians 1:20 is found:

&quot;For He rescued us from the domain of darkness, and transferred us to the kingdom of His beloved Son, in whom we have redemption, the forgiveness of sins.
He is the image of the invisible God, the firstborn of all creation. For by Him all things were created, both in the heavens and on earth, visible and invisible, whether thrones or dominions or rulers or authorities—all things have been created through Him and for Him. He is before all things, and in Him all things hold together. He is also head of the body, the church; and He is the beginning, the firstborn from the dead, so that He Himself will come to have first place in everything. For it was the Father’s good pleasure for all the fullness to dwell in Him, and through Him to reconcile all things to Himself, having made peace through the blood of His cross; through Him, I say, whether things on earth or things in heaven.&quot; {Colossians 1:13-20}

The greater context of the immediate passage, let alone the rest of the letter to Colossae, describes Christ's matchlessness, His supremity, etc.
Given that without Christ creation cannot exist, and given that Christ was sent to earth to save the elect of God, and given that eventually all will be made right at His second coming, the &quot;all things&quot; Paul references truly are &quot;all things&quot; (not all people, though, as some are not elected to be saved and are instead, like the Devil and his angels, condemned to eternal punishment).