Pejorative for a Christian (esp. an evangelist) of apparent low-intelligence who adheres strictly and illiberally to religious scripture; a Bible-thumper
Etymology: Merger of Bible + retard
People who seriously believe and proudly declaim that a supernatural being created a man out of dirt, women out of said man's rib, allowed a talking snake to beguile them into disobeying his express commands - leading to mankind's fall and downward spiral into iniquity - and then sacrificed himself to himself into order to rectify this state of affairs are nothing short of complete and utter bibletards.
A person who preaches scripture that they clearly do not understand and have no business reciting.
The other day some Bibletards knocked on my door and chatted shit for ages. I had to correct the Bibletards on a number of things they'd interpreted wrongly.