As a church history professor, I am sometimes asked how certain practices developed in church history. For example: When did the Roman Catholic (and Eastern Orthodox) emphasis on praying to saints and venerating relics and icons begin? A somewhat obscure, but extremely helpful, book by John Calvin answers that question directly.In his work, A Treatise on Relics, Calvin utilizes his extensive knowledge of church history to demonstrate that prayers to the saints, prayers for the dead, the veneration of relics, the lighting of candles (in homage to the saints), and the veneration of icons are all rooted in Roman paganism. Such practices infiltrated...