What was Paul's purpose in writing Ephesians?

The Epistle to the Ephesians was not actually written to the Ephesians, but was an encyclical to the Church as a whole. In contrast to Paul's own use of the term church (ekklesia, congregation), which he used only to refer to a local congregation, the author of Ephesians used the term in the singular to refer to the universal Church, and the opening address to the Ephesians is probably a late addition. Ephesians is supposedly addressed to a community of only Gentile Christians, but scholars doubts whether such a community yet existed in Pauline times.

The Epistle to the Ephesians copied much material from the pseudo-Pauline letter to the Colossians, which was in turn written sometime during the 70s.