St Peter Favre was one of the first Jesuits. He spent part of his career in Germany helping to reconvert Protestants to the Catholic faith. An excerpt from one of his letters (ca. 1565) to the second Superior General of the Society of Jesus, Diego Lainez, is a helpful reminder to the faithful:
“Whosoever desires to become useful to the heretics of this age must be solicitous to bear them much charity and to love them truly, excluding from his mind all thoughts which tend to cool his esteem for them. Secondly, it is necessary to gain their good-will, so that they may love us and keep a place for us in their hearts. This we can achieve by familiar intercourse with them, speaking of the things we have in common and avoiding all contentious argument ….
“When we meet a man, not only perverse in his opinions but evil in his life, we must set about to persuade him to abandon his vices before speaking to him of his errors in belief. It has happened to myself, for instance, that a man came wanting me to satisfy him about some erroneous views which he held, especially concerning the celibacy of the clergy. I dealt with him in such a way that he unburdened his conscience to me, on which lay the mortal sin of many years’ concubinage. I persuaded him to abandon that life … and no sooner had he done so and found himself by God’s grace able to live without a woman, than he renounced his errors, without saying another word about them. … Such people have need of admonitions and exhortations on morals, on the fear and love of God, on good works, to counter their frailties, distractions, tepidities and other afflictions, which are not principally or in the first place from the understanding, but from the hands and feet of the body and soul.”
Cited from Christopher Dawson, The Dividing of Christendom (New York: Sheed and Ward, 1965), 150-51