I recently came across a discussion amongst Christians that said that Buddhism (and Jainism) are actually not as compassionate as they make out to be. The main writer, a Christian scholar with considerable familiarity with "Dharmic religions" (his term), said that Buddhists, when confronted with a person or animal in the last stages of agony, one that cannot be saved, must in the end simply walk away, doing nothing to relieve the person's, or animal's, suffering.
How do we respond to this without sounding terribly callous? Thank you for any help!