I’m never going to be an astronaut, an Olympic sprinter, or a world-famous artist. Even if I pushed aside all distractions and spent the rest of my life pursuing those goals, it would be impossible to chart a path to success. No amount of desire and effort would be enough to get me there—even apart from the unstoppable march of time, I simply lack the capacity.
The same is true for most of us. Despite the dreams and unspoken hopes you might harbor, some things are simply beyond your capacity to achieve. But that’s not cause for mourning—on the contrary, it’s good to know your limitations. In some cases, it’s even encouraging.
For example, consider the apostle Paul’s charge to believers in Philippians 2:12 to “work out your salvation with fear and trembling.” Put simply, it’s a charge to work out the spiritual fruit the Lord has already worked into us through salvation.
But is that something we can do on our own? Are righteousness, integrity, and godly living simply matters of wanting it enough and trying hard?
Of course not. In fact, Paul acknowledges as much in the next line of his epistle: “for it is God who is at work in you, both to will and to work for His good pleasure” (Philippians 2:13). In his book The Power of Integrity, John MacArthur explains the great encouragement of that simple, familiar verse.
Working out our salvation would be useless—and indeed impossible—if it were not balanced by the truth of Philippians 2:13, “For it is God who is at work in you, both to will and to work for His good pleasure.” The glory of Christian living is that God calls us to obey and then effects that obedience in us. Our progress in sanctification demands all that we are, but it also demands all that God is in us. In John 15:5 Jesus says, “I am the vine, you are the branches; he who abides in Me and I in him, he bears much fruit; for apart from Me you can do nothing.” When you see spiritual fruit in your life, realize that God produced it: “There are varieties of effects, but the same God who works all things in all persons” (1 Corinthians 12:6).
I wonder how many Christians take for granted the awesome reality that God is actually in us—not merely working on us or for us, but truly in all genuine believers. . . . We can be assured that He did not go to great lengths to justify us and then leave us alone to work out our own sanctification. Galatians 3:3 says, “Are you so foolish? Having begun by the Spirit, are you now being perfected by the flesh?” Obviously, the answer Paul expects to this question is a resolute “No.” 
That ought to be a tremendous comfort to us. After salvation, we’re not left to manufacture godly habits and righteous behavior. The integrity of your life and testimony isn’t simply a question of trying hard enough. Our spiritual growth is not merely up to us—it’s produced and protected through the work of the Spirit in us.
John MacArthur highlights two aspects of the Spirit’s sanctifying work in us: “According to Philippians 2:13, the twofold purpose for God’s working in us is to cause us ‘to will and to work.’ That means the Lord wants to energize our desires and our actions.” 
Desiring What Is Right
The purity and consistency of your life is not solely determined by how you act. As we’ve seen throughout this series, true integrity starts on the inside, with your desires, inclinations, and intentions. If your will is not aligned with God’s, it doesn’t matter how you act.
As John MacArthur explains, it’s not a matter of your fluctuating and volatile emotions, but of where the affections of your heart are permanently fixed.
The Greek verb for “will” in verse 13 does not refer to passion, lust, or whimsical emotion. Rather, it focuses on intent and inclination—the dispassionate will of one’s studied, planned purpose. . . . God’s power moves within us to make us willing to live godly lives, to do and say what is right and just, and to walk with integrity. 
Specifically, the Spirit works in our will through two tandem motivations. The first is righteous discontent—not with our circumstances, but with the weakness of our spiritual state. It’s the sentiment Paul expressed in Romans 7:24 when he cried out to God, “Wretched man that I am! Who will set me free from the body of this death?” God works to promote an uncompromising godliness in us by helping us hate our sinful weaknesses.
Another motivation goes hand-in-hand with our righteous discontent—holy aspiration. John MacArthur describes this second motivating attitude as a longing “to be purer, holier, more righteous, and more genuine in our walk with Christ than we have been—a longing to be virtuous in our lifestyle and have victory over sin.” 
The result of those inward motivations ought to show up in how we act.
Working Out What Is Right
Through the Spirit’s influence, we’re not merely motivated to godliness—we’re enabled to live with true righteousness and integrity. As John MacArthur explains, it’s the Spirit who animates our good works.
God works in us so we’ll be able to do deeds of righteousness. Paul gives us a glimpse of the scope of this process when he prays, “Now to Him who is able to do exceeding abundantly beyond all that we ask or think, according to the power that works within us . . .” (Ephesians 3:20). Our omnipotent God can and does accomplish through us that which is unimaginable, beyond our ability to plan or dream. 
However, John is quick to point out that we are not merely puppets—that we bear our share of the responsibility for our growth in godliness.
None of the things we’ve just discussed, however, will be fully realized in our lives if we do not exercise self-discipline. It’s unscriptural and just plain wrong to think we can progress in godliness simply on good intentions and warm feelings regarding the Christian life. The Lord can work effectively only through lives that are disciplined and submitted to Him. 
With that in mind, though, we still need to cling to Paul’s encouraging, uplifting reminder of the Spirit’s work within us, especially as it pertains to living righteous, uncompromising lives. As John explains, it ought to shape our attitude about the work of integrity.
The incomprehensible truth of verse 13, that God is enabling us to live for Him and is pleased when we do, makes all the challenge and effort of working out our salvation with fear and trembling worthwhile. And it should give us all the encouragement and incentive we’ll ever need to live with integrity and without hypocrisy before the world (cf. 1 Corinthians 15:58). 
Source: God’s Role in Your Integrity