If you are always remembering Him by your activities and seeing Krishna everywhere, even in the heart of the demonic persons, then anger will never overcome you, being purified of all false pride. But occasionally if there is good reason, you may have to become angry just to chastise the evil-doers and blasphemers. We have seen that Lord Caitanya once nearly killed Jagai and Madhai for their offenses to His devotee, so, like that, if there is offensive behavior to the pure devotees you may become like Nrsimhadeva and punish them severely.
Letter to Niranjana, 29 August, 1972