NOTE: This is a condensed excerpt from my forthcoming (2014) commentary on Philippians.
Here in verse 12 Paul stresses that his circumstances have really served to advance the gospel. On a human level, one would expect that Paul’s imprisonment would slow or perhaps even stop the progress of the gospel. After all, Paul cannot plant churches while in Roman custody. But, as Paul states elsewhere “the foolishness of God is wiser than men, and the weakness of God is stronger than men” (1 Cor 1:25). The irony is that while Rome has imprisoned Paul in an effort to prevent his message from spreading, that very imprisonment has become the means by which the gospel advances. Paul may be in chains, but the gospel runs free. That is the surprising but true state of affairs.
In referring to the advance of the gospel, Paul uses a rare word (prokopē) that occurs just one other place in the New Testament outside of this letter. As part of his instructions to Timothy, Paul tells him to put them into practice “so that all may see your progress” (1 Tim 4:15). The term was commonly used to refer to progress in moral virtue or wisdom, especially in Philo and Stoic literature. But here it refers to the progress of the gospel, which advances like a disciplined Roman legion cutting its way through enemy opposition.
By framing the discussion of his circumstances within the context of the progress of the gospel, Paul makes it clear that the gospel is of utmost importance. Rather than complain about the difficulty of his circumstances, Paul revels in the advance of the gospel. Just as Joseph saw that what his brothers meant for evil God meant for good (Gen 50:20), so too Paul sees the sovereign hand of a good God behind the evil intentions of his Roman captors.
Paul’s commitment to the progress of the gospel is a needed reminder to the church today. It is easy for believers to get distracted with a plethora of activities and concerns, many of them good things. But do they advance the gospel? Perhaps more pointedly, is the progress of the gospel our primary concern as believers?
 Such a translation is an attempt to bring out the sense rather than woodenly follow the Greek, which reads something like “have come more into/for the progress of the gospel.”
 The Greek word translated “really” (mallon) could also be rendered “rather” (BDAG 3). If it means really, Paul’s point is one of intensification (“what has happened to me has definitely served to advance the gospel”); see, e.g., Jerry L. Sumney, Philippians: A Greek Student’s Intermediate Reader (Peabody: Hendrickson, 2007), 19. If it means rather, Paul’s point is one of contrast (“[contrary to what you expect] what has happened to me has served rather to advance the gospel”); see, e.g., O’Brien, Philippians, 90. The context favors the latter.
 The verb translated “has served” is actually erchomai, which normally means “come.” But here it is part of an idiomatic expression that means “result in furthering” (BDAG 5). The perfect tense of the verb emphasizes the state of affairs resulting from Paul’s circumstances.
 Speaking of celebrating the Passover, Philo writes “For while meditating on the migration from the passions and sacrificing the passover you ought to take the advance [prokopēn] towards perfection” (Leg 3:165; see also Leg 2:81; 3:249 [2x]; Pot 1:46; Agr 1:157; EBR 1:82; FUG 1:176). According to the sophist Diodorus Siculus, Pythagoras and his followers were unable to escape envy from their fellow Greeks “even though Pythagoras himself and the Pythagoreans after him made such advancement [prokopēs] [in wisdom] and were the cause of so great blessings to the states of Greece” (Diodorus Siculus, Bibliotheca Historica 10.10.2). A Greek wordplay between “advance” (prokopē) and “hindrance” (proskopē) may also be in view here (Hansen, Philippians, 67).
 Cp. Vincent, Philippians, 16.