What did Paul mean when he commanded to 'work out your own salvation'?

(This article is adapted from a response I posted publicly in 2014 to this question.)

"Therefore, my beloved, as you have always obeyed, not as in my presence only, but now much more in my absence, work out your own salvation with fear and trembling;"

-Philippians 2:12 (NKJV)

In the neverending debate between monergists (often called "calvinists") and synergists (arminians and others), one of the verses one might encounter is Philippians 2:12. If not read carefully, one could be led to believe that Paul is saying here that it is the sinner who must "work" towards his own salvation. That the sinner must "do a work" to be saved. But this would be in contradiction to what he says in several other passages in his epistles. Given that the Bible does not contradict itself, what could this phrase mean?

Perhaps a slight (yet grammatically sound) rearranging of the phrase might help clarify:

"let the outworking of your salvation be with fear and trembling,"

A few clues from the context tell us this phrasing (and hence meaning) are what is intended. The first clue is how he addresses his intended audience:

"Therefore, my beloved, as you have always obeyed.."

-Philippians 2:12a (NKJV)

Paul was directing this letter to those who had "always obeyed" and were his beloved. In other words, it is directed to fellow believers in the church at Philippi. If there is confusion as to whether he is referring to "working towards" your salvation, the next verse (which is still the same sentence) clarifies that right away:

"for it is God who works in you both to will and to do for His good pleasure."

-Philippians 2:13 (NKJV)

So,

"work out(wardly) what God is working in you"

is perhaps the simplest way to understand the meaning Paul was trying to convey. If that is still not clear enough, we can always go to the previous chapter where we find this:

"being confident of this very thing, that He who has begun a good work in you will complete it until the day of Jesus Christ;"

-Philippians 1:6 (NKJV)

Paul leaves no space for doubt -- it is God who begins, and completes the "good work" in believers, the work of salvation, and the subsequent work of sanctification. So, again, the "working out" of a believer's salvation is the "outworking" of something that has been done in them. Something the Savior has done, something God began and will see to its completion.

In the passage in question, Paul is trying to strongly encourage the believer, who has already been supernaturally saved by the completed work of Christ on the cross, to live in accordance with that truth (Matthew 3:8).

It is yet another passage where Paul is exhorting and teaching the parameters of Christian living, of a life of holiness (Philippians 2:15) with the added encouragement and motivation that, after all, it is God's working in us that accomplishes it, and is ultimately for His glory and His delight (Philippians 2:13).

This too sheds light on the second part of the verse, where he says the believer must do so in "fear and trembling". A strange addition for sure. But for the believer, we already know that

"The fear of the Lord is the beginning of wisdom"

-Proverbs 9:10a (NKJV)

While on the other side of the coin, a man whose heart does not desire to honor God is proving that he has an unregenerate heart -- that he is unsaved. Understanding this should strike fear and trembling in that heart, because dying in that unregenerate state makes it permanent.

So let us heed Paul's warning and encouragement. If you haven't already, repent, and put your trust exclusively in the completed work of Christ on the cross, outside of which there is no salvation or any help in the work of salvation. And, having been saved, work outwardly what God is already working inwardly in us. Live a life that is pleasing to God.