Paul concludes this long section regarding the Philippians' "affairs" on the note of suffering with which it began (1:29-30), punctuated in this case with rejoicing, thus recalling 1:18 (and 2:2). The key to how Paul gets here from verse 16 lies in his bringing himself—and his relationship with them—back into the picture in that verse. Although the but with which these final sentences begin signals a new sentence, it also stands in clear contrast to the "not in vain" at the end of verse 16. But what follows is so abrupt, and the metaphor so unusual, that the connection is not immediately obvious.
The form of the sentence is conditional, in this case expressing a real, not suppositional, condition. Thus (literally): "But if indeed I am being poured out like a drink offering in connection with the sacrifice and service of your faith, I rejoice." The metaphor itself is taken from the Jewish sacrificial system. Pictured is the burnt offering (thysia, "sacrifice"), the service itself (leitourgia) and the drink offering poured out at the sanctuary (spendo) in connection with (not "on" in Jewish ritual) the sacrifice (cf. Num 28:1-7). In 2 Timothy 4:6 Paul uses the metaphor of "being poured out like a drink offering" to point to his expected imminent death. But that is unlikely the intent here, since he is so "confident in the Lord" that he will be released (Phil 2:24; cf. 1:24-26)—not to mention that in 1:30 he has emphasized that he and the Philippians are undergoing "the same struggle," and their dying as the result of suffering is simply not in view in this letter.
Most likely, then, the whole clause is a metaphor for the present suffering that both he and they are experiencing at the hand of the Empire. He pictures his imprisonment as the drink offering that goes along with their "burnt offering," their present struggle in Philippi. That also means that the opening conjunction (ei kai) is not to be taken as concessive ("even though") but as intensive, "if indeed this is happening" (as the case really is). Given the return to this imagery in conjunction with their gift in 4:18, one is also tempted to see their "service of faith" (NIV service coming from your faith) as going beyond their present suffering and including their gift to him, which not only continued their commitment of friendship but was undertaken under their difficult present circumstances.
If this is how we are to understand the if part of the clause, then what of the connection with verse 16? The logic seems to be that rather than Paul's having run in vain, which in fact is unthinkable, his present suffering, which is also on their behalf in the midst of their own suffering, presents the real picture of their relationship. What is missing is an implied middle step. Thus the whole would go something like "I expect you to be my grounds for boasting at the day of Christ, evidence that I have not labored in vain. (And presently my labor includes imprisonment, as yours does suffering in Philippi.) But if indeed my present struggle represents a kind of drink offering to go along with your own suffering on behalf of the gospel, then I rejoice."
The "then" part of the sentence deliberately recalls 1:18. Even in the midst of what appear to be untoward circumstances, one's relationship with God does not change. At this point several matters about this theme in Philippians need to be noted. First, "joy" is primarily a verb in Philippians; it is something one does, not how one feels (as in the NIV's am glad). Second, as the reiteration of the imperative in 3:1 and 4:4 makes clear, "rejoicing" is not related to one's circumstances but is "in the Lord," as in the scores of Old Testament texts (especially in the Psalter) that Paul is echoing. That is, "rejoicing in the Lord" is part and parcel of Christian life and is quite unrelated to the present lay of the land. Indeed, this present text is very much reminiscent of the conclusion of Habakkuk's lament (3:17-18):
Though the fig tree does not bud
and there are no grapes on the vines,
though the olive crop fails
and the fields produce no food,
though there are no sheep in the pen
and no cattle in the stalls,
yet I will rejoice in the LORD,
I will be joyful in God my Savior.
This is not "sour grapes," nor making the best of a bad situation, nor "delight in feeling bad"; this has to do with true faith, and thus perspective, based as it is on the unshakable foundation of the work of Christ, both past and future.
Since Paul is so completely at home in the world of Scripture, as God's very Word, and since he really believes that "to live is Christ, to die is gain," he simply expresses this confidence in a thoroughly biblical way. Despite the constant "room service" he is provided (see 1:13), it is not the Rome Hilton, in a room with a view, where he currently finds himself. Yet his perspective is the right one, so "I rejoice," on my own as it were, but since we are in this thing together, I . . . rejoice with all of you as well. Which, of course, invites them to rejoice in the Lord by presuming that they are already doing so!
But just in case, he invites them to reciprocate: "In the same way you also rejoice (on your own, as it were), and then join me in rejoicing together" (see v. 19). To this point every mention of "joy," except in 1:25, has had to do with Paul. With this imperative in verse 18 a subtle, but noticeable, shift toward them takes place. What began in 1:25 as concern for their "progress and joy in the faith" is now put into the form of an imperative, an imperative that will recur at further points in the rest of the letter; significantly, its first occurrence is totally intertwined with Paul's joy and is found in the context of rejoicing in the midst of suffering and opposition.
Here, then, is the most likely reason for this otherwise unusual conclusion to the long appeal of 1:27—2:18. Paul has already modeled joy in the face of opposition and suffering (1:18); his concern for the Philippians is with both their "progress" and their "joy" regarding the gospel. Now, in anticipation of the renewal of their joy at the coming of Epaphroditus (2:28) and the imperative to "rejoice in the Lord (always)" that frames the final exhortation (3:1; 4:4), Paul begins by linking that imperative to his own joy, both in the context of present suffering and in the mutuality of that suffering.
Two significant theological points emerge here. First, we must not lose sight of the fact that everything else that is said is brought to bear on the opening imperative: Do everything without complaining or arguing. Because most of us are good at such behavior, it is easy to dismiss this as "mundane"; but the very fact that Paul spends so much energy giving biblical and theological support to it suggests otherwise. This is spoken in the context of their—and our—being God's children in a fallen, twisted world. Our corporate behavior, especially as that is reflected in our attitudes toward one another, goes a long way toward determining how effectively we hold out the word of life in such a world. Thus evangelism is the bottom line, and internal bickering among the people of God is thoroughly counterproductive activity.
Second, Paul's use of the story of Israel (in this case its failure) as his way of including the Philippians as God's people—indeed, as the true continuity of his people—says much about our own place in God's story. Again, the concern is with our behavior—with our succeeding where Israel failed. The underlying theology in all of this is God's own character, as that is now reflected in his children who bear his likeness as we live out the life of the future in the present age. Only as we reflect God's own likeness will our evangelism be worth anything at all, in terms of its aim and in terms of success.