The final phrase of Philippians 2:13 addresses the the purpose for God’s active work in the Christian’s life.
(ESV, NKJV, NASB) for his good pleasure.
(NET Bible) for the sake of his good pleasure
(NLT, Expanded Bible) what pleases him.
(Voice Bible) what always pleases Him.
(HCSB) His good purpose.
Again it is interesting to note that the thought for thought translations miss a subtle point. They state that God works in the believer to do what pleases him, which is the end result, but they miss the fact that God has a purpose for working in the believers life and it is to bring himself pleasure.
This concept that God works ultimately for his own pleasure is captured beautifully in Psalm 115:3.
Psalm 115:3 (ESV) — Our God is in the heavens; he does all that he pleases.
This understanding was first introduced to me in the early 1990’s when my dad gave me my first book by John Piper called “The Pleasures of God”, subtitled “Meditations On God’s Delight In Being God”. I highly recommend the book, if you want to understand what brings God pleasure.
Here are some other verses that speak to God doing what he pleases or purposes.
Psalm 135:6 (ESV) — Whatever the Lord pleases, he does, in heaven and on earth, in the seas and all deeps.
Exodus 33:19b (ESV) — And I will be gracious to whom I will be gracious, and will show mercy on whom I will show mercy.
Job 42:2 (ESV) — “I know that you can do all things, and that no purpose of yours can be thwarted.
Isaiah 14:24 (ESV) — The Lord of hosts has sworn: “As I have planned, so shall it be, and as I have purposed, so shall it stand,
Isaiah 46:9–10 (ESV) — remember the former things of old; for I am God, and there is no other; I am God, and there is none like me, declaring the end from the beginning and from ancient times things not yet done, saying, ‘My counsel shall stand, and I will accomplish all my purpose,’
In summary here is the entire passage again.
Philippians 2:12b–13 (ESV) — work out your own salvation with fear and trembling, for it is God who works in you, both to will and to work for his good pleasure.
I understand this passage to teach that I need to actively participate with God in the process of being saved (also called sanctification). This does not speak against that fact that I am in one sense already saved (justification), or that one day I will be saved (glorification), but while on this earth I need to take very seriously the call to work with God to transform my life into the likeness of Christ. I need to do this with a proper understanding of who God is in contrast with who I am, an understanding that will instil holy fear and trembling. At the same time I approach God with the view that apart from him I can do nothing to accomplish this, but I have the wonderful assurance that God wants to work in me to accomplish my sanctification since it is ultimately for his own pleasure.