The following is an excerpt from The MacArthur New Testament Commentary on Ephesians 2.

And you were dead in your trespasses and sins, in which you formerly walked according to the course of this world, according to the prince of the power of the air, of the spirit that is now working in the sons of disobedience. (Ephesians 2:1–2)

A person who is spiritually dead has no life by which he can respond to spiritual things, much less live a spiritual life. No amount of love, care, and words of affection from God can draw a response. A spiritually dead person is alienated from God and therefore alienated from life. He has no capacity to respond. As the great Scottish commentator John Eadie said, “It is a case of death walking.” Men apart from God are spiritual zombies, the walking dead who do not know they are dead. They go through the motions of life, but they do not possess it.

In the state of spiritual death, the only walking, or living, a person can do is according to the course of this world, according to the prince of the power of the air, of the spirit that is now working in the sons of disobedience. Kosmos (world) does not here represent simply the physical creation but the world order, the world’s system of values and way of doing things—the world’s course. And as Paul makes clear, the course of this world follows the leadership and design of Satan, the prince of the power of the air.

What we often call “the spirit of the times” reflects the wider course of this world, a course in which men are in basic agreement about what is right and wrong, valuable and worthless, important and unimportant. Sinful men have many different ideas and standards, but they are in total agreement that the network of things in this world is more important than the divine perspective of God. In this most basic world outlook they are of one mind. They resolutely work to fulfill the goals and values of their system, though it defies God and always self–destructs. Sinners are persistent in their rejection, and the worse their system becomes, the more they try to justify it and condemn those who speak the Word of God against it.

They are of one mind because they have a common leader and lord, the prince of the power of the air. Satan is now “the ruler of this world,” and until the Lord casts him out (John 12:31) he will continue to rule. The power [or authority] of the air probably refers to Satan’s host of demons who exist in the heavenly sphere. Paul has this in mind in Ephesians 6:12, where he warns of “the spiritual forces of wickedness in the heavenly places.” During the present age he and his demon host dominate, pressure, and control every person who is unsaved. He is the personification of spiritual death because he is the personification of rebellion against God—and so is the system he designed.

Satan is the archon, the prince and ruler over this world system. Not all unsaved people are necessarily indwelt at all times by Satan or are demon–possessed. But knowingly or unknowingly they are subject to Satan’s influence. Because they share his nature of sinfulness and exist in the same sphere of rebellion against God, they respond naturally to his leading and to the influence of his demons. They are on the same spiritual wavelength.

As with the world, the air over which Satan has controlling power represents the sphere where demons move. The air could be used metaphorically, as when we speak of an “air of expectancy:” In this context world and air would be almost synonymous, both of them representing a realm, or sphere, of influence. In that case it would be a reference to the realm of ideas, beliefs, and convictions over which Satan now operates as prince. But it is not that which is in Paul’s mind here or in 6:12. He has in mind the fact that Satan rules the power (demons) who occupy the air (the heavenly sphere around the earth). Men are not free and independent; they are totally dominated by the hosts of hell.