English Standard Version (ESV) for context:
Ephesians 2:2 (ESV) "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." This is part of a letter by the Apostle Paul to the Ephesians, in which he's reminding them of their past life before becoming followers of Christ. The verse has theological concepts, so let's break it down.
"And you were dead in the trespasses and sins": This phrase talks about the spiritual death of the Ephesians (and all people, by extension) because of their sins. The Bible often uses "death" to signify a spiritual separation from God, the source of life. Sin, in this context, is any act or thought that goes against God's laws and nature.
"in which you once walked": This phrase reinforces the idea that the Ephesians lived, in the past, in a way that was contrary to God's will. Walking is often used as a metaphor for one's life.
"following the course of this world": Here, "the course of this world" is used to describe the common patterns, behaviors, and values of human society that are often in contrast to God's values. It refers to the worldly influences that encourage sin and disobedience against God.
"following the prince of the power of the air": This phrase is generally interpreted as referring to Satan, who is described in other parts of the New Testament as the ruler of the world's corrupt system (see John 12:31, 14:30, 16:11). The "air" could symbolize the unseen spiritual realm, indicating that Satan's influence is pervasive.
"the spirit that is now at work in the sons of disobedience": This phrase continues the thought of the previous one. The "spirit" refers to the spirit of disobedience that characterizes those who live apart from God and in opposition to His ways. "Sons of disobedience" is a Jewish idiom that means "people characterized by disobedience."
Overall, Ephesians 2:2 underscores the contrast between the Ephesians' former way of life (characterized by sin and spiritual death) and their new life in Christ. It portrays a bleak picture of the human condition without Christ—being spiritually dead, controlled by worldly influences, and under the sway of evil forces.