11 And God was doing extraordinary miracles by the hands of Paul, 12 so that even handkerchiefs or aprons that had touched his skin were carried away to the sick, and their diseases left them and the evil spirits came out of them. 13 Then some of the itinerant Jewish exorcists undertook to invoke the name of the Lord Jesus over those who had evil spirits, saying, “I adjure you by the Jesus whom Paul proclaims.” 14 Seven sons of a Jewish high priest named Sceva were doing this. 15 But the evil spirit answered them, “Jesus I know, and Paul I recognize, but who are you?” 16 And the man in whom was the evil spirit leaped on them, mastered all of them and overpowered them, so that they fled out of that house naked and wounded. 17 And this became known to all the residents of Ephesus, both Jews and Greeks. And fear fell upon them all, and the name of the Lord Jesus was extolled.
God was doing extraordinary miracles by the hands of Paul at Ephesus, a city famous of the worship of Artemis and witchcraft. These miracles were directly identified as acts of power of the Holy Spirit who is working through him. "Extraordinary" is from the Greek root word tynchanō and has the idea of "accurate," "effective," or "hitting the target." "By the hands of Paul" means the miracles came through Paul, not necessarily only from his hands but even those who touched his skin were healed.
In the Gospels, some people were healed by touching Jesus' robes (Mat 9:20–22; 14:34–36). However, this does not validate the modern practice of "prayer handkerchiefs." There are televangelists who sell pieces of cloth they claim to have the power to heal, earn money, or otherwise send God's blessings. Demanding money for a magical piece of fabric is for frauds and the greedy for money.
Seeing what Paul did, some itinerant Jewish exorcists undertook to invoke the name of the Lord Jesus over those who had evil spirits. They were the seven sons of Sceva, a Jewish high priest. They used the name of Jesus. Fraudsters often take advantage of the search for a deeper connection to the spirit world. During their first missionary journey, they had encountered one in Cyprus named Bar-jesus.
However these exorcists use the sounds that identify the Jesus Paul worships, they don't use Jesus' name. Why? His name includes His power, sovereignty, character, and authority. When we are baptized in Jesus' name, we submit ourselves to Him. To use Jesus without really knowing Him is to risk His rejection. Clearly, Jesus says, “Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven. On that day many will say to me, ‘Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?’ And then will I declare to them, ‘I never knew you; depart from me, you workers of lawlessness.’ [Matt 7:21-23]
It's also to risk being ignored, even worse to be attacked by the demons being addressed. The man in whom was the evil spirit leaped on them, mastered all of them and overpowered them, so that they fled out of that house naked and wounded.[v.16] The evil spirit could make their lives miserable. As Mark wrote, “And whenever it seizes him, it throws him down, and he foams and grinds his teeth and becomes rigid.”[Mark 9:18]
In other words, God would expose the fraud. Ironically, He even used the demon to expose their folly and extoll the integrity of Paul. The spirit answered, “Jesus I know, and Paul I recognize, but who are you?” The people in response feared God. Thereby, their wicked ways was turned around as a means for God’s glory. In the Old Testament, He even could use an animal, a donkey spoke and exposed Balaam’s wickedness. God can turn things around for He is in control. God and the Spirit’s work could neither be misappropriated nor duplicated.