Wherein in time past ye walked according to the course of this world, according to the prince of the power of the air, the spirit that now worketh in the children of disobedience:
The course of this world - the career (literally, 'the age:' cf. Galatians 1:4) or present system of this world (1 Corinthians 2:6; 1 Corinthians 2:12; 1 Corinthians 3:18-19), as opposed to "the world to come;" not gradually ameliorating, but progressively deteriorating: alien from God, and lying in the wicked one (1 John 5:19). 'The age' х aioon (G165)] (something internal and ethical) regulates 'the world' х kosmos (G2889)] (something more external).
The prince of the power of the air - the unseen potentate who lies underneath, guiding "the course of this world" (2 Corinthians 4:4); ranging through the air - i:e., the whole region between earth and heaven (cf. Mark 4:4, "fowls of the air" (Greek, 'heaven') - i:e., Ephesians 2:15, "Satan" and his demons). Compare Ephesians 6:12; John 12:31. Christ's ascension cast Satan out of heaven (Revelation 12:5; Revelation 12:9-10; Revelation 12:12-13; Revelation 12:15; Revelation 12:17), where he had been heretofore, the accuser of the brethren (Job 1:7). No longer able to accuse in heaven those justified by Christ, the ascended Saviour (Romans 8:33-34), he assails them on earth with all trials and temptations: 'we live in an atmosphere poisoned and impregnated with deadly elements; but a mighty purification of the air will be effected by Christ's coming' (Auberlen), for Satan shall be bound (Revelation 20:2-3). "The power" is here collectively for the 'powers of the air;' in apposition with which 'powers' stands "the spirit," taken also collectively: the aggregate of the "seducing spirits" (1 Timothy 4:1) which 'work now (still. not merely, as in your case, "in time past") in the sons of disobedience (a Hebraism: men not merely by accident disobedient, but whose essential characteristic is disobedience: cf. Matthew 3:7), and of which Satan is "the prince." х Tou (G3588) pneumatos (G4151)] "The spirit" is in apposition, not to Satan, "the prince" х archonta (G758)], but to х exousias (G1849)] 'the powers of the air,' of which he is prince. The powers of the air are the embodiment of that evil "spirit" which is the ruling principle of unbelievers (Acts 26:18), as opposed to the spirit of the children of God (Luke 4:33). The potency of that "spirit" is shown in the "disobedience" of the former (cf. Deuteronomy 32:20; Isaiah 30:9; Isaiah 57:4). They disobey the Gospel in faith and practice (2 Thessalonians 1:8; 1 Corinthians 2:12). But Ellicott, 'prince of the empire of the air, of the (evil) principle that now worketh,' etc.