The fundamental theme of the epistle is The Unity of Mankind in Christ, and hence the Unity and Divinity of the Church of Christ.
The relationship, both literary and theological, between the epistle to the Ephesians and that to the Colossians is very close.
If the latter epistle could be finally established as genuine, or its date fixed, it would give important evidence with regard to Ephesians; but in the present state of discussion we must confine ourselves to pointing out the fact.
De Wette first (1826) doubted, then (1843) denied that the epistle was by Paul.
But the more serious difficulties which to many minds still stand in the way of the acceptance of the epistle have come from the developed phase of Pauline theology which it shows, and from the general background and atmosphere of the underlying system of thought, in which the absence of the well-known earlier controversies is remarkable, while some things suggest the thought of John and a later age.