Contra Robert M. Bowman, there is sufficient reason to construe QEOS in Philippians 2:13 as the subject rather than the predicate of the syntactical construction. Rogers and Rogers Linguistic and Exegetical Key points out that QEOS (Philippians 2:13) is fronted which indicates that it's the subject rather than the predicate (see p. 452).
John Calvin also seems to understand QEOS as the subject in this verse. Calvin writes: "God,'says he, 'is hO ENERGWN TO ENERGEIN he that worketh in us to do.' He brings, therefore, to perfection those pious dispositions which he has implanted in us, that they may not be unproductive, as he promises by Ezekiel, --'I will cause them to walk in my commandments.'"
(Ezekiel 11:20.) See his commentary on Philippians.