"'There's an epidemic of powerless worship leaders,' pastor William McDowell says - ...In this account, Paul shared how he was used mightily by God which even allowed him to transfer healing and deliverance to others by sending handkerchiefs as a point of contact. Then the story introduces seven others, named the sons of Sceva, who were just imitating followers of God and were overpowered by a demon because they had no authority in God for themselves..."
https://www.christianpost.com/news/theres-epidemic-of-powerless-worship-leaders-pastor-william-mcdowell-says.html 
