15. Resolved, Never to suffer the least motions of anger toward irrational beings
Given that anger is an emotional response of displeasure to someone's wrongdoing, then I understand such person as acting irrationally when he doesn't reason before or while performing his action. Conversely, someone is rational when he acts with premeditation and when to a fair extent he is aware both of the motives that drive him to action and of its consequences.
But are we to read the resolution between lines and conclude that is legitimate to feel angry at rational beings? Wasn't that Jesus' experience? Indeed, He became angry at those who were testing him by asking whether healing on a Sabbath was lawful. They weren't questioning him out of lack of knowledge nor because they were crazy. So, it is understable and right for Jesus to feel angry at them because he knew clearly the motives -they wanted to seek a fault to accuse him- behind their questioning. They weren't irrational at all.
But what about us? We can't clearly look at other peoples' motives! However, we can pray for them and for the situation. We can also reason with them, namely asking questions to clarify our own understanding of their actions and discern whether they have been acting rationally or not.
Now, there would be cases when we would not even try reasoning with them. If they are under the effect of alcohol or drugs or with a mental illness then they are not acting rationally even if they harm us. In such cases, anger is not a proper response. By getting angry at them and by acting driven by such anger we would not only be wasting time and energy. We would be sinning by taking revenge in our own hands rather than trusting God who will ultimately does us justice. Indeed God's counsel is: "overcome evil with good"(*)
May it be so.
19 Beloved, never avenge yourselves, but leave it  to the wrath of God, for it is written, “Vengeance is mine, I will repay, says the Lord.” 20 To the contrary, “if your enemy is hungry, feed him; if he is thirsty, give him something to drink; for by so doing you will heap burning coals on his head.” 21 Do not be overcome by evil, but overcome evil with good. (Romans 12:19-21)
(*)The implications of this principle are vast and are out of the scope of this short reflection. It will suffice to say that this overcoming involves not only a passive response on our behalf but also an active one. For the latter, we must be thankful to God for legislation passed within our own societies in order to minimize irrational behavior in the citizens of the state.