Not Turning the Other Cheek
But the moment you introduce other factors, of course, the problem is altered. Does anyone suppose that Our Lord's hearers understood Him to mean that if a homicidal maniac, attempting to murder a third party, tried to knock me out of the way, I must stand aside and let him get his victim? I at any rate think it impossible they could have so understood Him. I think it equally impossible that they supposed Him to mean that the best way of bringing up a child was to let it hit its parents whenever it was in a temper, or, when it had grabbed at the jam, to give it the honey also. I think the meaning of the words was perfectly clear--"Insofar as you are simply an angry man who has been hurt, mortify your anger and do not hit back"--even, one would have assumed that insofar as you are a magistrate struck by a private person, a parent struck by a child, a teacher by a scholar, a sane man by a lunatic, or a soldier by the public enemy, your duties may be very different, different because [there] may be then other motives than egoistic retaliation for hitting back.
~C.S. Lewis, The Weight of Glory, "Why I Am Not a Pacifist" (1949)