The term “Spirit” is clearly a reference to the Holy Spirit, the third person of the holy Trinity. The additional word “of glory” seeks to point up the glorious nature of the Spirit, that is, the Spirit possessing glory. The word “glory” itself refers to the gravitas and weightiness that belong to the Godhead, and so also to the Spirit. This Spirit works sanctification (1 Peter 1:2) so that sinners are changed in such a way that they can live lives of holiness (1 Peter 1:14–16) befitting a “spiritual house” (1 Peter 2:5). The additional words “and of God” do not denote another Spirit (that is, one of glory and another of God), but provide a further elaboration of the “Spirit of glory, that is, (the Spirit) of God.” It is in the Spirit that Jesus Christ lives in his people (John 14:23; Romans 8:9).
14 If you are insulted for the name of Christ, you are blessed, because the Spirit of glory and of God rests upon you.