Clues from the Immediate Context of the Verse Itself
In Eph 2:2, this "ruler" (τὸν ἄρχοντα) is clarified as to what he rules over. This clarification comes, as is common with this word, in the form of a genitive case noun.1 However, there is a series of four genitives that follow:
- "the authority" (τῆς ἐξουσίας)
- "the air" (τοῦ ἀέρος)
- "the spirit" (τοῦ πνεύματος)
- "the [one] now working in the sons of disobedience" (τοῦ νῦν ἐνεργοῦντος ἐν τοῖς υἱοῖς τῆς ἀπειθείας)
Just taking the first two genitives to begin with, there are two possible meanings:
- "of the authority over the air" (i.e. the ruler has the rights of control over the air)
- "of the power of the air" (i.e. the ruler has control of what the air has power to do)
The two meanings are possible because a genitive associated to "authority" (ἐξουσίας) can be either an objective or subjective genitive,2 that is respectively, what is being ruled over by authority or what is possessing the authority.
What one finds with either rendering of the two genitives, it amounts to the same idea: this ruler controls the air such that what the air has power to do, this ruler has power over it.
The air (ἀέρος) is strictly speaking of the atmosphere, sky, etc., generally as we think of it,3 minus our more scientific understanding in this day. As such, in the immediate context, it does not help much to identify who this "ruler" is.
However, the last two genitives inform us more about this ruler, for he is in some way associated with "the spirit," specifically, "the [one spirit] now working in the sons of disobedience." The final genitive in the sequence is a participle phrase that is describing "the spirit." It could be rendered "the spirit which now works in the sons of disobedience."
The question is, why the genitive for "the spirit" (τοῦ πνεύματος)? If "the spirit" was renaming "the ruler," it would have been in the accusative case as an appositive to the accusative case used for "the ruler" (τὸν ἄρχοντα). That means either the genitive is intended to be an appositive to the preceding genitive, or it is intended to be an additional extended object of what is "ruled" over. So it means on of these two:
- "... the air, which is the spirit which now works in the sons of disobedience" (i.e. the air is the spirit)
- "the ruler ..., of the spirit which now works in the sons of disobedience" (i.e. the ruler commands both the air and the spirit working disobedience)
For the question at hand, identifying "the ruler," we discover it does not really matter whether 1 or 2 is correct, because in either case the ruler who has authority over the air is also the one having authority over that which works in the sons of disobedience.
And this ruler's "path" is parallel to being "according to the age of this world" (κατὰ τὸν αἰῶνα τοῦ κόσμου τούτου) by the parallel "according to the ruler..." (κατὰ τὸν ἄρχοντα). This is the path that those Paul is immediately addressing "once walked" (ποτε περιεπατήσατε) in, implying (and later explicitly stated) they walk no more in.
So far the immediate evidence from the verse tells us then:
- The ruler is over a direction the audience is no longer following
- That direction is in accord with the age of this world
- The ruler is over the air or the air's authority
- The ruler is over the spirit (which may be the same as the air) which controls the direction of people to be in disobedience
Finalization from the Context of Ephesians
This ruler's direction is soon contrasted with another direction, the direction of one having faith in being saved by God's grace in Christ (Eph 2:4-9), which direction leads to good works (i.e. not disobedience; Eph 2:10, cf. Eph 4:1). The one with such salvation was "once" partaking in the direction of the ruler of Eph 2:2, having not been saved, but rather part of the "children of wrath" (Eph 2:3). Compare also Eph 4:17-19 (disobedience) with 4:20-24 (obedience), and really continued contrast with much of the rest of Ephesians after 4:24.
So from this, we know that "the ruler" of 2:2 is not referring to God or Christ, based off the contrast. Yet that ruler, and the power and authority he possesses, are all ultimately under the final authority of the exalted Christ, who is "seated ... far above all principality [ἀρχῆς] and power [ἐξουσίας] and might [δυνάμεως] and dominion [κυριότητος]" (Eph 1:20-21; NKJV).
Notice the first two words referring to what Christ is over (ἀρχῆς, ἐξουσίας) are related to, or the same word as, the words in Eph 2:2 (ἄρχοντα, ἐξουσίας). Later, it is further learned that there are "principalities and powers in the heavenlies" (ταῖς ἀρχαῖς καὶ ταῖς ἐξουσίαις ἐν τοῖς ἐπουρανίοις; Eph 3:10) that something is being made known to (indicating they are "personal" beings referred to, ones that can gain "knowledge").
Paul also, later, returns to use the air with respect to false teachings, when he exhorts those who are no longer walking with this ruler:
that we should no longer be children, tossed to and fro and carried
about with every wind [ἀνέμῳ] of doctrine, by the trickery of men, in the
cunning craftiness of deceitful plotting (Eph 4:14, NKJV)
The word "wind" (ἀνέμῳ) is not the same word as used in Eph 2:2, but the conceptual link is evident, as the wind is the air's movement, or even more so, the power evidenced by the air—air's power. The purposeful, figurative use of this phrasing here in Eph 4:14, to me, seems like a strong allusion back to Eph 2:2.
There is a long continued contrasting of the two directions through Ephesians chapters 4 and 5, of which space and time do not permit examining. But we do find two important points made related to the contrast of directions that also appear to isolate who is "the ruler" of the wrong direction:
- Those walking in the right way are to guard against "giving place to the devil" (Eph 4:27) by walking again in the wrong way.
- Those walking in the right way are to be prepared to "stand against the wiles of the devil" (Eph 6:11).
While "giving place to the devil" may allude to the idea of "air" (which is empty space as a place), that would be a weak connection. More important with the Eph 4:27 passage is the fact that by walking wrong, one is basically ceding to the devil's ways (which does relate to the disobedience).
More important is the Eph 6:11 verse, for the "wiles [μεθοδείας] of the devil" refers to his "schemes" or methods,3 which conceptually relates both to the direction "according to" which disobedient people walked that "the ruler" ruled over (Eph 2:2) and the "wind of doctrine" to be avoided (Eph 4:14).
Additionally, the Eph 6:11 passage is in the same context as referring to the subject matter of rulers and authority, for in v.12 it states the opposition is:
principalities [ἀρχάς], against powers [ἐξουσίας], against the rulers [κοσμοκράτορας] of the darkness of
this age, against spiritual hosts [πνευματικὰ] of wickedness in the heavenly places (NKJV; "heavenly places" or "heavenlies")
The methods of the devil, then, are in relation to the opposition from "rulers" (ἀρχάς; i.e. "principalities" above), and "authorities" (ἐξουσίας; i.e. "powers" above), and "world-controllers"/"world-holders"/"world-rulers" (κοσμοκράτορας; i.e. "rulers" above), and "spiritualities" (πνευματικὰ; i.e. "spiritual hosts" above). Notice three of the terms relate to the Eph 2:2 statement: ἀρχάς, ἐξουσίας, and πνευματικὰ.
The revelation from Eph 6:11 is that the methodology put out by the devil is enacted through rulers, authorities, world-controllers, and spiritualities that are not "flesh and blood" (Eph 4:12a), but spiritual persons (as Eph 3:10 noted as well).
So the apostle Paul (who I do take to be the writer of the epistle; Eph 1:1), in referring to the ruler of Eph 2:2, later clarifies the statement to be the one in charge of the direction of things against God, the things of disobedience, which is the devil, according to Eph 6:11-12.
Ephesians 2:2 is probably best translated like so (my opinion):
In which once you walked, according to the age of this world,
according to the ruler of the authority over the air, the spirit who
now works in the sons of disobedience
Where "the ruler" is the devil (per Eph 6:11), "the authority over the air" is one of the spiritual "authorities" against God (per Eph 6:12) under the scheming of the devil (per Eph 6:11), which spiritual authority is also the same spirit working in disobedient people (latter part of Eph 2:2), by carrying those people about with false doctrine spoken (speech goes through the air) to them by men in disobedience (per Eph 4:14).
If so, it means the direct answer to your question of who is "the authority over the air" is that spirit under the devil's rule with such authority, which then makes the devil himself the chief commander of the air through his underling.
Note, however, that if "authority of the air" does mean the "air's power," then the ruler himself is the one over the air.
Yet again, in either case, the one calling the shots with respect to the air is the devil. This matches with prior revelation as well, assuming one associates the devil with Satan as Rev 12:9 and 20:2 do. This is because Job 1:6-19 indicates that Satan used disobedient men (the Sabeans, 1:15, and Chaldeans, 1:17), "fire of God from heaven" (lightning most likely, but from the air, 1:16, and further showing Satan's power to direct actions God has allowed him to direct; i.e. what God has given him authority over), and a great wind (also air's power, 1:19) to work destruction on the righteous Job. The parallel is not likely a coincidence on Paul's part.
Whether the destruction by air aspects were also enacted by a spiritual underling of Satan, as the men were acting as underlings against Job, or by Satan directly becomes somewhat of a mute point.
The devil, Satan, is the one with authority of, or authority over the spirit who has authority of, the air and the disobedient people within humankind.
1 Daniel Wallace, Greek Grammar Beyond the Basics - Exegetical Syntax of the New Testament (Zondervan, 1999), 103. He refers to it as a "genitive of subordination," which is usually a "subset of the objective genitive."
2 William Arndt, Frederick W. Danker, and Walter Bauer, A Greek-English Lexicon of the New Testament and Other Early Christian Literature (Chicago: University of Chicago Press, 2000), s.v. ἐξουσία, #3, gives examples "W. gen. of the one who has authority" or "W. gen. of that over which the authority is exercised." NOTE: Hereafter, this work will be referenced by the common BDAG abbreviation.
2 BDAG, s.v. ἀήρ.
3 BDAG, s.v. μεθοδεία.