"ISKCON members speak knowingly of happiness. Don't followers of Kṛṣṇa conscious ever get angry?"
Yes. They can get angry. Why not? They're very much angry to the nondevotees: "You rascal! Why you are not surrendering yourself to God? You rascals." Yes. We are angry. This anger is service of Kṛṣṇa. How can I give up anger? But we use anger in a different way, not for our sense gratification: "Why you have not paid me such-and-such money?" No, we don't say like that. "Why you are not Kṛṣṇa conscious?" That is our anger.
So the anger can be utilized in Kṛṣṇa consciousness. Everything can be utilized in Kṛṣṇa consciousness. Why should I give up anger? Kṛṣṇa is also angry, and I am son of Kṛṣṇa. So anger is in me because I have got the qualities of my father. So how can I give up anger? But I use anger only for Kṛṣṇa. So we do not leave anything, but we utilize everything for Kṛṣṇa. That is our Kṛṣṇa consciousness philosophy. So, "Don't followers of Kṛṣṇa conscious ever get angry?" Yes, we get angry. Why not? We are not artificial. Human nature is to become anger, sometimes satisfied, sometimes . . . so we utilize this. We are angry when one is not Kṛṣṇa conscious, when he's against God.