Paul identifies himself and then adds a qualification, calling himself “a prisoner for Christ Jesus.” The Greek genitive case is used and could also be rendered as “a prisoner of Christ Jesus.” Paul uses the same appellation (“a prisoner for”) in Philemon 9 (cf. Eph. 4:1). The term “prisoner” (desmios) appears to be intended in a nonfigurative sense to indicate that Paul’s liberty has been forcibly curtailed rather than being a metaphorical expression of his relationship to Christ. This is confirmed by various references to his imprisonment in this letter (vv. 10, 13, 23). Contrast his use elsewhere of doulos Christou (“servant of Christ”; Rom. 1:1, etc.), which does not indicate that Paul was a slave within Greco-Roman society.
Paul chooses not to identify himself as an apostle, as he does when his authority is in question (e.g., Gal. 1:1). Perhaps this is because he does not need to do so when writing personally to his friend Philemon, or perhaps he chooses not to do so for the sake of rhetorical strategy. If the latter is the case, Paul may be deliberately describing himself in language suggesting a low social status in order to identify with Onesimus, who indeed has a very low social status. Nonetheless, it is interesting that Paul chooses not to use the term doulos as a self-reference (as he does, e.g., in Phil. 1:1) when the issue at hand involves slavery in society.
Paul’s condition as a prisoner is qualified by the phrase “of Christ Jesus.” The genitive construction can be translated in a variety of ways. For example, as Pao points out, it might be understood as indicating that Paul is a prisoner “because of preaching about Jesus Christ,” “for the sake of Jesus Christ,” or “belonging to Jesus Christ,” among other possibilities. Although Constantine Campbell identifies the genitive as a “possessive genitive,” Pao is probably correct to indicate that it is best not to limit the meaning of the genitive too strictly in this case.
Timothy is associated with the letter as one of Paul’s colleagues (cf. 2 Cor. 1:1; Phil. 1:1; Col 1:1; 1 Thess. 1:1), but the rest of the letter is written using first-person pronouns. This suggests that Timothy did not have a significant impact on the content of the letter; it is Paul’s voice that we hear. Timothy may, however, have acted as Paul’s scribe. Paul’s approach to his ministry is decidedly communal, and Timothy is named because his service alongside Paul is deeply valued (cf. Phil. 2:20). Paul calls Timothy “our brother,” using family language for the relationship between Christians. Although the ESV uses the first-person plural pronoun “our,” the Greek reads simply “the brother,” using the definite article. Nevertheless, Paul is probably indicating that a relationship with Timothy, established by God’s grace rather than by human kinship, is one that both Paul and Philemon share.
Philemon is identified as the recipient of the letter using simply his name in the dative case. This is then qualified by a Greek phrase composed of two elements joined by “and.” These two elements might be translated “the beloved” and “fellow worker.” The ESV treats these as a composite description highlighting both the warmth of the personal relationship between Paul and Philemon and also the bond established by their common cause. Lightfoot suggests it probably would have been during Paul’s lengthy stay in nearby Ephesus (cf. Acts 19) that he would have been a “fellow worker” with Philemon, although the uses of this term with reference to Christians in the church at Rome in the greetings in Romans 16:3 and 9 suggest that Paul did not need to be physically present with someone to regard that person as a fellow worker. The term agapētos (“beloved”) may also suggest something more than simply the warmth of human friendship, perhaps used by Paul to suggest that the one loved is loved not only by Paul but ultimately by God (cf. Rom. 1:7).
Paul further develops his distinctive greeting by adding the term eirēnē, “peace.” This word brings to mind the Hebrew term shalom, referring to wholeness in all respects. BDAG suggests understanding the word as referring to “a state of concord” or “well-being” (BDAG, s.v. εἰρήνη). In Paul’s usage, eirēnē may express a desire that the believer would experience peace with God through reconciliation achieved by Jesus Christ, and also peace with the Christian community and with society in general. Thus, through some minor adjustments in terminology, Paul transforms a relatively routine greeting into a deeply theological prayer for the spiritual and social well-being of his Christian brothers and sisters.