Senders (1a): Like 1 & 2 Thessalonians, the senders of this letter are multiple people: Paul and Timothy. However, unlike those letters, which continually speak from 1st person plural, the remainder of this letter is written from the 1st person singular point of view. After this initial greeting, the speaker is never "we" but "I"—the Apostle Paul. Timothy is present as a silent contributor, and this book reflects the mind and the heart of the Apostle Paul.
Recipients & Greeting (1b-2): The recipients are the Philippian Christians described as "the saints" plus its leadership: "overseers and deacons." This is the structure of the church as we have seen in our study of biblical deacons. As Paul always does, he wishes his audience "grace" and "peace" that comes from God our Father and the Lord Jesus Christ. These warm words communicated comfort to the Philippians during a time when they were facing persecution.
Thanksgiving (3-4): Paul then immediately expresses thanks to God for them. We should keep in mind that Paul himself is suffering for the gospel when he writes this letter. He is imprisoned in Rome. His thanksgiving shows he practiced what he preached. He said: "in everything give thanks" (1 Thess. 5:18), and he himself gave thanks even while in prison! What a helpful reminder for us to do the same even in the midst of our times of trials. Now, this thanksgiving is offered to God in prayer. This isn't just a grateful feeling but an actual expression of thanks to God. God has accomplished a wonderful work among the Philippians, and that work of God is explained in 1:5-8.
The Work of God (5-8): The work of God is seen in three ways in these verses. First, it is their "participation in the gospel" (1:5). This is their financial support of Paul's gospel ministry from the time they were first evangelized by him. And who caused them to participate in the gospel this way? God did! Hence, He is the One thanked. Second, the Philippians joined in defending and confirming the gospel. They also stood by Paul by sending Epaphroditus to minister to him during his imprisonment for "the defense of the gospel" (1:16). And again, God is the One who made them into such partners in the gospel! Third, God started and guaranteed the completion of their salvation. That is the "good work" described in verse 5. And who began this "good work" and who will complete it? God, of course! He saved them. He made sinners into the generous, committed, and faithful defenders of the gospel, and He will see to it that their salvation reaches its full completion! Thanks be to God! To this, Paul also adds that they are the object of Christ's affections (1:8), and as such, they also have the affections of Christ's slaves like the apostle. Thanks be to God who lavishes His people with the affections of Christ even through the earthly expressions of love from His slaves!
 "in no way alarmed by your opponents… For to you it has been granted for Christ's sake… to suffer for His sake, experiencing the same conflict which you saw in me" (1:27-30).
 Imprisonment is described in 1:7 ("my imprisonment in the cause of Christ") and Roman location implied in 4:22 ("All the saints greet you, especially those of Caesar's household").
 "I thank my God… always offering prayer with joy in my every prayer for you all" (1:4).
 "from the first day" is later explained "at the first preaching of the gospel… no church shared with me in the matter of giving… but you alone" (4:15). "until now" refers to the latest gift sent to him at this time (4:18).
 "who is also your messenger and minister to my need" (2:25).
 2:13 describes salvation as God's ongoing work as it does here. Also, the particular verbs for "begin" and "perfect" used here occur together elsewhere only in Gal. 3:3 where it also describes salvation.
 "bond-servants" (1:1) is the Greek word dou-los (δοῦλος) which means "slaves" (in the plural).
 "how I long for you all with the affection of Christ Jesus" (1:8). Timothy is another example (2:19-21).