An individual who lives by the principles of the Bible, and follows the teachings of Jesus Christ as a way of life. Jesus' followers are called Christians. A Christian is a disciple of Jesus, and a disciple means a follower. Bible thumpers (aka Christians) live by the fact that the Bible is the living Word of God, and live their lives in a way that pleases and glorifies God, in order to assure salvation in heaven.
You know Jason? He's a Bible thumper. He's always trying to convert me into Christianity, because the Bible is telling him to. He keeps on telling me that I'll be going to hell if I don't accept Jesus as my Lord and Saviour.