Summary: Satan is always on the prowl, and the biblically-taught Christian is "not ignorant of his schemes".
I. THE FALLEN SPIRIT CALLED SATAN
Scripture is clear about Satan’s very real and personal existence. he was once the chief angel, the anointed cherub, the star of the morning, who sparkled with all the jewels of created beauty - until he rebelled against his Creator and tried to usurp His power and glory (see Isa. 14:12-17; Ezek. 28:1-10; Rev. 12:7-9). He first appears in Scripture in the form of a serpent, as he tempted Adam and Eve (Gen. 3:1). Jesus not only spoke about Satan (Luke 10:18; John 8:44; 12:31) but spoke with him (Matt. 4:3-10). Paul, Peter, James, John, and writer of Hebrews all speak of him as a personal being (Rom. 16:20; 2 Cor. 2:11; 1 Thess. 2:18; Heb. 2:14; James 4:7; 1 Pet. 5:8; Rev. 12:9). We see him opposing God’s work (Zech. 3:1), perverting God’s Word (Matt. 4:6), hindering God’s servant (1 Thess. 2:18), hindering the gospel (2 Cor. 4:4), snaring the wicked (1 Tim. 3:7), appearing as an angel of light (2 Cor. 11:14), and fighting with the archangel Michael (Jude 9). He brought sin into the world and the whole world now lies in his power (1 John 5:19).
The Bible refers to the devil by such personal names and descriptions as “the anointed cherub” (Ezek. 28:14), “the ruler of demons” (Luke 11:15), “the ruler of this world” (John 16:11), “the god of this world” (2 Cor. 4:4), “the prince of the power of the air” (Eph 2:2), and numerous others. He is identified as the great dragon, a roaring lion, the vile one, the tempter, the accuser, and the spirit working in the sons of disobedience. Fifty-two times the devil, which means “slanderer.” This fallen archangel and his fallen angels who became demons have been tempting and corrupting mankind since the Fall. They are an evil, formidable, cunning, powerful, and invisible foe against whom no human being in his own power and resources is a match.
II. THE SCOPE OF HIS ENGAGEMENT
Even God’s holy angels face opposition when they minister for Him. The angel sent to Daniel was opposed by a demon for twenty-one days and had to be assisted by the archangel Michael (Dan. 10:13), and Michael even had a battle with Satan himself over the body of Moses (Jude 9).
To the Thessalonian church Paul reflected on his battle when he said, “For we wanted to come to you - I, Paul, more than once - and yet Satan thwarted us” (I Thess. 2:18). Believers are attacked personally and corporately.
Paul warned the elders from Ephesus, “I know that after my departure savage wolves will come in among you, not sparing the flock; and from among your own selves men will arise, speaking perverse things, to draw away the disciples after them” (Acts 20:29-30). They would be attacked both from the outside and the inside. Satan is always on the prowl, and the biblically-taught Christian is “not ignorant of his schemes” (2 Cor. 2:11).
(((The MacArthur N. Testament Commentary:Ephesians; pgs 332-333, 338-339)))