Galatians 3:27

baptized into Christ-- (Rom 6:3). have put on Christ--Ye did, in that very act of being baptized into Christ, put on, or clothe yourselves with, Christ: so the Greek expresses. Christ is to you the toga virilis (the Roman garment of the full-grown man, assumed when ceasing to be a child) [BENGEL]. GATAKER defines a Christian, "One who has put on Christ." The argument is, By baptism ye have put on Christ; and therefore, He being the Son of God, ye become sons by adoption, by virtue of His Sonship by generation. This proves that baptism, where it answers to its ideal, is not a mere empty sign, but a means of spiritual transference from the state of legal condemnation to that of living union with Christ, and of sonship through Him in relation to God (Rom 13:14). Christ alone can, by baptizing with His Spirit, make the inward grace correspond to the outward sign. But as He promises the blessing in the faithful use of the means, the Church has rightly presumed, in charity, that such is the case, nothing appearing to the contrary.

— Jamieson-Fausset-Brown Commentary (public domain)