The first time I read verse 12 I thought I had misread it. Then I wondered if St. Paul was talking out of both sides of his mouth, for he seems to have contradicted himself in the very next verse. How do I “work out” my salvation when it is God who is working in me? The answer is in how one translates the Greek. This time the Asbury Commentary stumbles all over these two verses, just like I did. Apparently John Wesley also missed this. Matthew Henry also seems to be uncertain about verse 12.
The IVP comments are a bit scholarly, but they provide insight. The overview, called Final Appeal, is most certainly worth reading. But the General Application makes it clear what St. Paul is doing. I will let you read what the IVP says, since they say it very well.
I found the IVP comments on vs. 14-16 and 17-18 useful. The concept of “Obedience” underlies all of this, from the Obedience of Christ in vs. 6-11 to working out our corporate salvation and our becoming blameless (which includes quarreling and complaining).
It should be apparent by now that St. Paul works his writer’s art well, crafting much meaning into just a few words. It occurs to me that the parchment/paper that was available was most likely quite expensive. So one would want to put as much meaning as possible into as few words as needed. But it could also be that God chose Paul because he was a lawyer, a man who understood the value and meaning of words. The best lawyers protect their clients with precise wording, exact meaning. I think the IVP commentator saw what Paul was doing in this passage. What do you think of Paul’s use of words?
Finally, there’s the situation in Philippi. C. S. Lewis used the word “bent” to describe humanity. We constantly “get it wrong” and thus we complain and quarrel. We whine over some bent idea we have about how “it ought to be” and forget about being a bent, sinful creature just like those we dislike. Someone offends us and we become self-righteous. Matthew Henry tells us about “Momus” and says we should conduct ourselves in such a way that even he cannot complain!
…Well, I’m not sure St. Paul meant that, but it does illustrate an ideal. Bear in mind that Jesus pointed out how the Pharisees complained about John the Baptist, only to complain when Jesus did the opposite. See Luke 7:33-34
One thing is certain: St. Paul wants us to imitate Jesus and he gave us a short poem to remember that we should adopt the mindset of Christ.