36 This charity, intelligent and sympathetic towards those even who offend you, does by no means imply a renunciation of the right of proclaiming, vindicating and defending the truth and its implications. The priest's first loving gift to his neighbors is to serve truth and refute error in any of its forms. Failure on this score would be not only a betrayal of God and your vocation, but also an offense against the real welfare of your people and country. To all those who have kept their promised fidelity to their Bishops on the day of their ordination; to all those who in the exercise of their priestly function are called upon to suffer persecution; to all those imprisoned in jail and concentration camps, the Father of the Christian world sends his words of gratitude and commendation.
Source: Mit Brennender Sorge (Vatican.va)