Albert Barnes Commentary Acts 19:18

"Many also of them that had believed came, confessing, and declaring their deeds." — Acts 19:18 (ASV)

Their deeds. Their actions; their evil course of life. Their deeds of iniquity in their former state. The direct reference here is to the magical arts which had been used, but the word may also be designed to denote iniquity in general.

Those who make a profession of religion will be willing to confess their transgressions. And no one who is not willing to confess as well as to forsake his sins can have evidence that he is truly renewed (Romans 10:10; Proverbs 28:13): He that covereth his sins shall not prosper; but whoso confesseth and forsaketh them shall find mercy.