1) Someone who is extremely evangelical in their religious belief. Many of them believe that their denomination is the one true denomination, and all others are wrong or evil. They try to make you feel like your life is a waste and use scriptures that have nothing to do with what they're saying to "explain" themselves.
2) Someone who screws with a very religious person.
Dude 2: "dude, you are a bible thumper! Didn't you get with that devout christian girl?
Their actions usually do more harm than good to their cause and bring into disrepute and ridicule those more reticent Christians.
He thinks everything in the bible should be taken literally; he's a foolish bible thumper.
See George W. Bush, John Ashcroft, Jerry Falwell, Pat Robertson, right-wing nutjob
often characterized by their constant refences to the bible and their intent on converting everyone in a 100 mile radius.
They are essentially the same as Islamic fundamentalists, with the same religous zeal and fantacism.
"Hands that help are far better than lips that pray."
bible thumper:you cant watch south park!its against christianity!!your going to hell!
me:dude, where does it say in the bible i cant watch a tv show?