Contrast the account of Stephen in Acts 6-7 with the account of the seven sons of Sceva in Acts 19 and we see an underlying theme that has crept into Christianity today. That theme is best described in a devotional book I recently found in our library which says; "Secondhand religion is always overpowered by firsthand evil…the impotence of the Church is caused by the secondhand nature of its religion. Jesus is never available if you are preaching a secondhand Jesus. It must be out of one's own depths to the depths of the other person. Only that which comes from the heart can reach the heart."
Stephen presented a "first hand" Jesus that he knew deep within the depths of his heart. This Jesus motivated and compelled him to share the greatest love he ever knew without consideration of his own well being. This heart dwelling knowledge and love of Jesus was not encountered by the sons of Sceva. Oh they knew of Jesus, but so did their attackers.
Our actions will always reveal Who really masters our hearts.