“against rulers, against authorities, against the powers of this dark world and against the spiritual forces of evil” (6:12)
Looking at the preceding sentence of this particular verse O’Brian states that the word rendered ‘struggle’ is not a common word used in the Greek Bible but one that is connected with a popular form of wrestling in the first Century in western Asia Minor. Speaking in terms of this battle that we have with spiritual forces, “Paul identifies with his readers (and, by implication, all Christians) in this spiritual conflict.”
Withrington understands the designation concerning rulers, authorities, powers of this dark world and spiritual forces of evil are actually amplifications of a single thread of understanding. Witherington explains that this “amplification indicates the dangerous nature of these beings.” Witherington’s thought follows the same pattern of understanding that O’Brian has on this.
O’Brian comments that the phrase ‘rulers and authorities’ denotes “those over whom Christ rules, both in this age and in the age to come.” The phrase, ‘the world-rulers of darkness,’ is an unfamiliar term in the NT corpus. ‘Word-rulers’ indicate demonic influences which appear either in the form of gods such as Sarapis or Hermes or Artemis. O’Brian continues that “the qualifying phrase of this dark world indicates that this potentates belong to this present evil age of darkness, a darkness from which believers have been delivered through Christ (5:8, 11; cf. Col 1:13).”
On the final phrase, ‘the spiritual host of evil’, “does not point to a separate category of cosmic powers but is a comprehensive term covering all classes of hostile spirits, while the additional phrase in the heavenly realms indicates their locality.” Although being powerful we need to note that these are subjected beings where they “rule the realm of darkness and evil, but Christians have been transformed out of this realm (5:8, 16; cf. Col 1:13).”
According to O’Brian these spiritual forces do not denote “structures of thought (tradition, convention, law, authority, and religion)” although we cannot deny that they can influence these structures. O’Brian further argues that “it fails to do justice to the historical context of the New Testament in which belief in the spiritual realm was widespread, it does not adequately account for explicit statements about these powers in Paul logically and hermeneutically.”
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Lincoln, Andrew T. Ephesians. (Dallas, Texas: Word.1990).
O’Brian, Peter. The Letters to the Ephesians. (Leicester, England: Apollos.1999).
Stott, John. The Message of Ephesians. (North Street, Nottingham: IVP,1989).
Talbert, Charles H. Ephesians and Colossians. (Grand Rapids, Michigan: Baker, 2007).
Witherington III, Ben. The Letters to Philemon, the Colossians and the Ephesians: A Socio-Rhetorical Commentary on the Captivity Epistles. (Grand Rapids, Michigan: Eerdmans,2007).
 Witherington III, Ben. The Letters to Philemon, the Colossians and the Ephesians. P.350
 O’Brian, Peter. The Letters to the Ephesians.,p.467