Contrary to popular belief, the Seven Deadly Sins never appear in the bible and were actually conceived as "eight evil thoughts" by a Christian monk named Evagrius Ponticus in the 4th Century as a guide to piety for his fellow monks. In the 6th Century, Pope Gregory I reworked the list into seven. Theologian Thomas Aquinas again revisited the list in Summa Theologica (“Summary of Theology”) and this is where we get the form in which we known them.