(2:9) Commenting on the contents of this verse, Lightfool says; “The apostle justifies the foregoing charge that the doctrine was not according to Christ: ‘In Christ dwells the whole plērōma (πληρωμα) (fulness, plenitude), the entire fulness of the Godhead, whereas they represent it to you as dispersed among several spiritual agencies. Christ is the fountain-head of all spiritual life, whereas they teach you to seek it in communion with inferior creatures.’ ”
“Dwelleth” is katoikei (κατοικει). Oikeō (Ὀικεω) means “to be at home.” Kata (Κατα), prefixed, means “down,” thus showing permanence. The compound verb was used of the permanent residents of a town as compared with the transient community. The verb is in the present tense, showing durative action. The translation reads: “Because in Him there is continuously and permanently at home all the fulness of the Godhead in bodily fashion.”
As previously discussed, that same "fullness" is found in Ephesians 3:19, where it applies to all Christians, without suggesting that all Christians are somehow part of a God-head.
The fact remains that there is no explicitly Trinitarian language in the New Testament, and that trinitarianism is an interpretation, valid certainly, but for some not necessarily the only valid interpretation.