Paul opens his letter to Philemon in a way that is unique to his writings when he uses the identification "a prisoner for Christ Jesus" to describe himself. Contrary to his normal custom, he adds no title of authority to his name, such as "apostle" or "servant of Christ".
By using this greeting, Paul emphasizes that he is not merely a prisoner or victim of religious intolerance. He is a prisoner of Jesus Christ, which he repeat in verse 10. In verse 13 he says that he is a prisoner for the gospel. Lohse notes that this phrase shows that Paul "considers his imprisonment as the fate that is in store for the messenger of the gospel – this is, part and parcel of the commission given to him. The messenger of the Kyrios must suffer like his master to whom he owed obedience."
It is obvious that this letter is to a dear friend, requesting a favour and he has no intention of invoking his apostolic authority. He entreats his friend (verses 8, 9) rather than commanding him. Perhaps he is emphasizing the sacrifice that he has made for serving Christ and he is about to ask his friend to also make a sacrifice. Philemon is being asked to forgive his runaway slave and to treat Onesimus not as a slave but as a brother (verse 16). He waives his authority to command Philemon (verse 9) as an old man and "a prisoner for Christ Jesus." He hopes that because of his age and his sacrifice that Philemon will be motivated to grant the request that he is about to make. Philemon must decide whether he will respond as a man of the world or as a servant of Christ. By referring to himself as a prisoner for Christ, Paul is reminding Philemon of the sacrificial decisions that he has made. Paul’s imprisonment is thus used to motivate Philemon to Christ-like behavior. It is if he were saying, "Surely you can do likewise dear friend."
Paul points out that it was specifically because of his imprisonment that Onesimus became a follower of Christ and his spiritual child (verse 10). He also mentions that he would have like to have kept Onesimus with him in his "imprisonment for the gospel" (verse 13). In such a situation, he needed help from others. While we are not told of the conditions of his imprisonment, it may be assumed that Philemon was familiar with what Paul was experiencing in his confinement. Besides, it is the fact of his imprisonment that is of fundamental importance to Paul in this letter, not the specific attributes of his chains. The fact that he desires help, however, suggests this Paul’s imprisonment did leave him in a situation of need where Onesimus’ absence would be keenly felt.
As an apostle, it is conceivable that Paul might have drawn upon his authority to insist on keeping Onesimus’ help during his time of need. It is obvious, however, that he did not want to show disrespect for Philemon’s authority as the slave’s rightful owner (verse 14). Moreover, it is conceivable that Paul recognized that just as force is no attribute of God, neither is it to be an attribute of His people. Rather than resorting to a show of compulsion and strength, Paul uses the power of persuasion and love.
He is confident that Philemon will accept his plea on Onesimus’ behalf and accept his slave as a brother, just as he would receive Paul, himself, were Paul able to be freed (verse 17). In fact, he is confident that Philemon will exceed his expectations (verse 21).
With such expectation, Paul instructs Philemon to prepare for his release (verse 22). The apostle expects to be freed, in answer to the prayer of Philemon and the Christian community (verse 22). He recognizes that the prayer will have a significant role in his release. Prayer, for Paul, was far more than just a spiritual way of saying, “Think about me from time to time.” It is through prayer that God will free him from his chains and restore him to fellowship with Philemon and the Christian community.
 1 Cor. 1:1; 2 Cor.1:1; Gal. 1:1; Eph. 1:1; Col. 1:1; 1 Tim. 1:1; 2 Tim. 1:1; Titus 1:1
 Romans 1:1; Phil. 1:1; Titus 1:1
 Ibid: 189.
 Eduard Lohse, Colossians and Philemon. Fortress Press, 1971: 199
 Richard J. Cassidy, “Paul’s Letter to Philemon” in The Bible on Suffering. ed. Anthony J. Tambasco. Paulist Press, 2002: 151; Richard J. Cassidy, Paul in Chains. The Crossroad Publishing Company, 2002: 75-76.
 Cassidy, Paul in Chains: 76
 Note that the Greek word for “you” used twice in verse 22 is in the plural.
 Cassidy, “Paul’s Letter to Philemon”: 156; Lohse: 207.