God. This use of the personal pronoun is frequent in Paul's writings. See Gal 3:16; Eph 4:8; 1Co 6:16.
Awake. etc.
The quotation is probably a combination and free rendering of Isa 60:1; Isa 26:19. For similar combinations see on Rom 3:10; see on Rom 9:33. By some the words are regarded as the fragment of a hymn.