Why did the religious Jews gnash their teeth at Stephen?
The religious Jews gnashed their teeth because Stephen’s words cut them to the heart, and their religious convictions drove them into a berserk rage. Civilized men lost all civility when confronted with conviction, becoming vicious in the name of religion rather than repenting.
Les explains that Stephen was building God’s case against the nation, and God was convicting their hearts. When they heard these things, they were cut to the heart and gnashed on him with their teeth. Les reminds us that people never get more vicious than when they do it in the name of religion. These were religious Jews, civilized people, but because of their religion they suddenly lost all their civility. They literally gnashed on him with their teeth, becoming berserk because of their convictions. Stephen, full of the Holy Spirit, looked up steadfastly into heaven and saw the glory of God and Jesus.
When they heard these things, they were cut to the heart, and they gnashed on him with their teeth.