By St. John the Prophet
Question 658: When I see someone insulting religion and blaspheming the holy faith, I am troubled against this person, supposedly out of zeal. What does this mean?
Response: You have certainly heard that no one can come to correction through evil, but rather only through good. Therefore, speak to this person with meekness and long-suffering, advising him in godly fear. And if you see that you are troubled, it is not necessary to say anything to him.
From The Letters of Saints Barsanuphios and John; translated by John Chryssavgis.