This was a search hit yesterday. And its a good question, a very good question.
Much of the authorship debate, I think is a result of genre confusions.
Ephesians is so different than Paul’s other letters in a number of ways, some of which relate to theological emphasis and other relate to form.
Ernest Best on both of this bases, argues that Ephesians is not written by Paul. He then turns around and says that Ephesians also is only a letter in a superficial sense. Its actually more of a homily or sermon.
When I read that in his commentary, I thought, “Wait, Best, if you had come to that second conclusion first, would you have needed to reject Pauline authorship?”
I doubt it. I think the form differences and the theology difference between Ephesians and Paul’s other letters can be explained by admitting that Ephesians should not be understood as a letter. Its a homily. Its a sermon – with a specific theological focus. Understood from this perspective, the problems disappear rather easily.
So then, “What genre is Ephesians?”
Ephesians is a homily wrapped up in a letter.