The Old Testament introduces a supernatural God and his supernatural enemy, Satan, a spiritual being that rebelled against God. Both God and Satan have underlings. The biblical story begins with God’s Creation; then Satan orchestrated the Fall. Instead of destroying Satan, God called Abraham to a relationship and a promise, which would shift to Abraham’s son Isaac, then to Jacob (renamed Israel), and then to Israel’s descendants. So, the Israelites were God’s beachhead in a world contaminated by Satan and its demons. Despite repeated betrayals, a remnant of every generation of Israelites remained faithful. Later, in the prophetic period of the Old Testament, God promised Israel a future Messiah who would set the world alright.
The New Testament begins with the arrival of that Messiah, Jesus Christ. Paradoxically, he would die to offer relationships and eternal life to all who would turn from the influences of Satan and put their faith in him. After Jesus’ crucifixion, resurrection, and Pentecost, the Spirit of Jesus redirected the Apostle Paul from unwittingly following Satan’s ways and commissioned him to launch an alternate “nation,” the Church, with members from every nation gathering regularly in local assemblies to worship Jesus as Lord. Paul traveled extensively, preaching and writing foundational letters to those assemblies. One of these letters went to Ephesus, the source for our verses.
The BibleProject’s The Satan and Demons and The New Humanity
Clifford Arnold’s Powers of Darkness (Especially notice Chapter 12 for help understanding the Armor of God described in Ephesians 6:10-20)
N.T. Wright’s Paul - a Biography, pg.297-301
Ralph Martin’s Interpretation: Ephesians, Colossians, and Philemon, pg.74-77
Andrew T. Lincoln’s Word Biblical Commentary, Ephesians, pg.454-460
My sermon collection: Powers of Darkness.