We've reached chapter 2 of Ephesians at last, but then of course that's an artificial designation. Chapter 2 continues a thought process with which chapter 1 ended. Paul has just been saying that the same power at work in Christ to raise him from the dead is at work in us who are, as Paul says so characteristically, "in Christ."
That's the larger point to be kept in mind as we go on. Paul is "illustrating" the power of God by reminding the Ephesians what God has already saved them from. The first 3 verses of chapter 2 (in the ESV) say this:
And you were dead in the trespasses and sins in which you once walked, following the course of this world, following the prince of the power of the air, the spirit that is now at work in the sons of disobedience, among whom we all once lived in the passions of our flesh, carrying out the desires of the body and the mind, and were by nature children of wrath, like the rest of mankind.To paraphrase: Having told the Ephesian believers that they have the same power working in them that worked in Christ Jesus to raise him from the dead, Paul now reminds them that they too were dead, after a fashion. He says, you have a destiny of blessings now, but back then you followed a different "course." You were dead in sin, helpless. Like a lifeless leaf on an Autumn wind, you just went with the flow. That might not sound so bad, except that this wind, you see, is ruled by "the prince of the power of the air." You had no motive-force within you to resist. You were, then, children of that prince, like him in his wrath and in his disobedience. As Jesus told the Pharisees, you were children of the devil.
This was what God saved you Ephesians from, says Paul. This then is the power at work within you. A power to pluck you from that wind-current, and set you stable on a Rock. Amazing, no? The next verses will reveal what God saved them for.