The Letter to the Ephesians
The letter to the Ephesians is traditionally understood to have been written by Paul while he was in prison (Eph 3:1, 4:1, 6:20). However, the identity of Paul as the author has been challenged, so before establishing a date for the letter, we should first address the question of authorship.
Unlike most other Pauline epistles, Ephesian does not contain personal greetings to any individuals in Ephesus. This is surprising, since the book of Acts describes a close and intimate relationship between Paul and the church there. Eph 1:15 could be read to indicate that the author had heard about the faith of the Ephesians without personally experiencing it - something that would not be true of Paul. However, this is not the only way to understand the verse. Interestingly, the phrase, "in Ephesus" in 1:1 is not in all manuscripts of the book, and there are no other references in the book that clearly tie the book to the actual church of Ephesus. Barclay and others have suggested that Ephesians was a circular letter (William Barclay, The Letters to the Galatians and Ephesians, p. 70) intended for multiple churches in the region.
Despite some objections, the overall evidence seems to weigh in favor of Pauline authorship. First of all, in Eph 1:1 the author calls himself Paul. Although it was not uncommon in that day to falsely attribute a writing to a more famous person in a sort of reverse plagiarism, this doesn't seem to be the case in Ephesians. The final closing has a promise to send Tychicus to Ephesus (Eph (6:21-22) with all the latest personal news about Paul. If this passage was not written by Paul, it would be a very subtle attempt at deception indeed. The theology of Ephesians is typical of Paul, with the emphasis on salvation by grace through faith and not works. The pattern of the book is also typical of Paul, with theology first and practical instructions afterward.
Ignatius of Antioch (37-107 A.D.) wrote to the Ephesians near the end of his life (Ignatius to Ephesians chapter 6) and said "And ye are, as Paul wrote to you, one body and one spirit, because ye have also been called in one hope of the faith. Since also there is one Lord, one faith, one baptism, one God and Father of all, who is over all, and through all, and in all. Such, then, are ye, having been taught by such instructors, Paul the Christ-bearer, and Timothy the most faithful." Ignatius here is quoting from Eph 4:4-6, and attributing it to Paul and Timothy. Since the life of Ignatius significantly overlapped that of Paul, his early witness to Pauline authorship is compelling.
This then is a letter written by Paul while he is in prison. Paul had an emotional parting from the Ephesian elders in Acts 20:17-38, and this imprisonment should be understood as being after that, either in Caesarea (57-59 A.D.) or Rome (60-62 A.D.). It is not possible to definitively decide which location is correct, but the best guess may be based on the connection between Ephesians and Colossians. Tychicus (Col 4:7, Eph 6:21-22) is bringing news of the imprisoned Paul in each. Since Colossians was apparently carried along with Philemon and a now unknown letter to Laodicea, it seems likely that all these letters were carried by Tychicus together, as a package. Ephesus was about 100 miles from Colosse, and a traveler from Rome to Colosse might pass through Ephesus. Thus, we should date the letter to the Ephesians in 61 or 62 A.D.