Colossians 2:9

For in him dwelleth - That is, this was the great and central doctrine that was to be maintained about Christ, that all the fulness of the Godhead dwelt in him. Every system which denied this was a denial of the doctrine which they had been taught; and against every thing that would go to undermine this; they were especially to be on their guard. Almost all heresy has been begun by some form of the denial of the great central truth of the incarnation of the Son of God.

All the fulness - Notes, Colossians 1:19.

Of the Godhead - Of the Divinity, the divine nature - θεότης theotēs. The word is one that properly denotes the divine nature and perfections. Robinson, Lexicon. It occurs nowhere else in the New Testament.

Bodily - σωματικῶς sōmatikōs. This word also is found nowhere else in the New Testament, though the adjective bodily - σωματικὸς sōmatikos - occurs twice; Luke 3:22, “in a bodily shape;” and 1 Timothy 4:8, “for bodily exercise profiteth little.” The word means, “having a bodily appearance, instead of existing or appearing in a spiritual form;” and the fair sense of the phrase is, that the fullness of the divine nature became incarnate, and was indwelling in the body of the Redeemer. It does not meet the case to say, as Crellius does, that the “whole divine will was in him,” for the word θεότη theotē - “godhead” - does not mean the will of God; and it is as certainly true that the inspired prophets were under the control of the divine will, as that the Saviour was. Nor can it mean, as Socinus supposes, that the fulness of divine knowledge dwelt in him, for this is not the proper meaning of the word (θεότης theotēs) “godhead;” nor can it mean, for the same reason, that a fullness of divine gifts was intrusted to him. The language is such as would be obviously employed on the supposition that God became incarnate, and appeared in human form; and there is no other idea which it so naturally expresses, nor is there any other which it can be made to express without a forced construction. The meaning is, that it was not anyone attribute of the Deity that became incarnate in the Saviour; that he was not merely endowed with the knowledge, or the power, or the wisdom of God; but that the whole Deity thus became incarnate, and appeared in human form; compare John 14:9; John 1:18. No language could, therefore, more clearly demonstrate the divinity of Christ. Of what mere man - of what angel, could it be used?