 The address provoked a strong reaction from the faculty , who denounced it as heretical , forcing Cop to flee to Basel . Calvin , a close friend of Cop , was implicated in the offence , and for the next year he was forced into hiding . He remained on the move , sheltering with his friend Louis du Tillet in Angoulême and taking refuge in Noyon and Orléans . He was finally forced to flee France during the Affair of the Placards in mid @-@ October 1534 . In that incident , unknown reformers had posted placards in various cities attacking the Catholic mass , which provoked a violent backlash against Protestants . In January 1535 , Calvin joined Cop in Basel , a city under the influence of the reformer Johannes Oecolampadius . 
