Adam Clarke's Commentary on the Bible

Verse 20 (Colossians 1:20)

And, having made peace through the blood of his cross - Peace between God and man; for man being in a sinful state, and there being no peace to the wicked, it required a reconciliation to be made to restore peace between heaven and earth; but peace could not be made without an atonement for sin, and the consequence shows that the blood of Christ shed on the cross was necessary to make this atonement.

To reconcile all things unto himself - The enmity was on the part of the creature; though God is angry with the wicked every day, yet he is never unwilling to be reconciled. But man, whose carnal mind is enmity to God, is naturally averse from this reconciliation; it requires, therefore, the blood of the cross to atone for the sin, and the influence of the Spirit to reconcile the transgressor to him against whom he has offended! See the notes on 2 Corinthians 5:19 , etc.

Things in earth, or things in heaven - Much has been said on this very obscure clause; but, as it is my object not to write dissertations but notes, I shall not introduce the opinions of learned men, which have as much ingenuity as variety to recommend them. If the phrase be not a kind of collective phrase to signify all the world, or all mankind, as Dr. Hammond supposed the things in heaven may refer, according to some, to those persons who died under the Old Testament dispensation, and who could not have a title to glory but through the sacrificial death of Christ: and the apostle may have intended these merely to show that without this sacrifice no human beings could be saved, not only those who were then on the earth, and to whom in their successive generations the Gospel should be preached, but even those who had died before the incarnation; and, as those of them that were faithful were now in a state of blessedness, they could not have arrived there but through the blood of the cross, for the blood of calves and goats could not take away sin. After all, the apostle probably means the Jews and the Gentiles; the state of the former being always considered a sort of Divine or celestial state, while that of the latter was reputed to be merely earthly, without any mixture of spiritual or heavenly good. It is certain that a grand part of our Lord's design, in his incarnation and death, was to reconcile the Jews and the Gentiles, and make them one fold under himself, the great Shepherd and Bishop of souls. That the enmity of the Jews was great against the Gentiles is well known, and that the Gentiles held them in supreme contempt is not less so. It was therefore an object worthy of the mercy of God to form a scheme that might reconcile these two grand divisions of mankind; and, as it was his purpose to reconcile and make them one, we learn from this circumstance, as well as from many others, that his design was to save the whole human race.

- Adam Clarke's Commentary on the Bible