Council of Trent (c. 1555) The General Council called to Trent (1545-63) by Pope Paul III (1468-1549) was charged with defining the Catholic beliefs contested by the Protestants and with instituting a general reform of the clergy and the laity. The bishops, in conjunction with theologians and diplomats, formulated the program that guided Catholic reform during the next 150 years. Oil painting by Jean Gilles Berizzi (c. 1485-1576), c. 1555.