Colossians 2:2 is not talking about the same concept. The mystery of God is not the same concept as Godhead. Colossians 2:2 is a great proof text AGAINST the Trinity. Here's what it actually says "God and Father" "And of the Christ". God and Father here are the same being. "And of the Christ" means another separate being. The Greek is delineating that "God and Father" is one being, and "Christ" is another being. The word "And" can be tricky, but the Greeks probably understood when it meant "The same being" and "a separate conjunctive object". "God and Father" is the same being, but not the Christ, because it's separated by the "And of".
HOWEVER, this verse apparently has some manuscript issues with different versions.
ΠΡΟΣ ΚΟΛΟΣΣΑΕΙΣ 2:2 Greek NT: Tischendorf 8th Ed. with Diacritics
ἵνα παρακαλέω ὁ καρδία αὐτός συμβιβάζω ἐν ἀγάπη καί εἰς πᾶς πλοῦτος ὁ πληροφορία ὁ σύνεσις εἰς ἐπίγνωσις ὁ μυστήριον ὁ θεός Χριστός
ΠΡΟΣ ΚΟΛΟΣΣΑΕΙΣ 2:2 Greek NT: Stephanus Textus Receptus (1550, with accents)
ἵνα παρακληθῶσιν αἱ καρδίαι αὐτῶν συμβιβασθέντων ἐν ἀγάπῃ καὶ εἰς πάντα πλοῦτον τῆς πληροφορίας τῆς συνέσεως εἰς ἐπίγνωσιν τοῦ μυστηρίου τοῦ θεοῦ καὶ πατρὸς καὶ τοῦ Χριστοῦ
In this event I think the Textus Receptus may have it right, but I'm not sure. Either way, that's the version you're going by, and it clearly differentiates "The God and Father" and "The Christ" as two different beings.