Phil. 2.13? (gram. subj.?)

So that newcomers don't get the wrong impression that they have
accidentally subscribed to the "b-Q" list rather than b-greek :) I'd like
to pose a question in a grammatical area. (I'm not complaining about the Q
thread;  it's been interesting even though prudence has suggested that I
keep my mouth shut and just listen!)

Phil. 2:13, 'Theos gar estin ho energwn en humin...'

1. Which is the subject ('Theos' or 'ho energwn')?
2. Is this a convertible or subset proposition?

Based on Porter's _Idioms..._, Wallace's _Exegetical Syntax_, and
McGaaughy's _Analysis of Einai_, I'm working with these guidelines: 

1. If one substantive is a pronoun (except interrogatives), it is the
subject.  This is true even if the pronoun is not explicitly stated but is
inherent in the verb.

2. If one of the substantives has an article or is a proper name, it is
the subject. 

3. If #2 is ambiguous, the nominative first in word order is the subject. 

Qualifications: These three are arranged hierarchically. (Thus a pronoun,
if present, is always the subject.) If both substantives meet the
qualifications of #2, the first (in word order) is the subject, but the
statement is to be treated as a convertible proposition (i.e., they are

My question re. Phil. 2:13 hinges, in part, on whether 'theos' is to be
treated as a proper name. Wallace says no (& I think I agree), but also
lists this text as a convertible proposition--which the above principles
would not allow, though the sense of the context suggests that it would
make no difference in this instance; i.e., 'the one who works in you is
God' is no different (semantically) than 'God is the one who works in

Any comments or suggestions?

Rod Decker
Calvary Theological Seminary, Kansas City