The nature writer Bill Bryson describes the treatment of the native Aborigines during the early days of Australia:

For most Europeans the Aborigines … it helped to regard them as essentially subhuman, a view that persisted well into the twentieth century. As recently as the early 1960s … schools were using a textbook that likened Aborigines to "feral jungle creatures"…. until 1967 the federal government did not even include them in national censuses—did not, in other words, count them as people.

[There are historical examples] of the most appalling cruelty by settlers toward the natives—of Aborigines butchered for dog food; … of another chased up a tree and tormented from below with rifle shots …. What is perhaps most shocking is how casually so much of this was done, and at all levels of society. In 1839 … a visitor [to Australia related] how he went out one day with "a respectable young gentleman" to hunt kangaroos. As they rounded a bend, the young gentleman spied a form crouched in hiding behind a fallen tree. Stepping over to investigate and "finding it only to be a native," the "gentleman" lifted the muzzle to the native's breast "and shot him dead on the spot."

Such behavior was virtually never treated as a crime …. Settlers were instructed to track down the offending natives and "inflict such punishment as they may merit"—as open an invitation to genocide as can be found in English law …. Sometimes, under the pretense of compassion, Aborigines were offered food that had been dosed with poison.

Possible Preaching Angles: (1) Sanctity of Life, Human Dignity, Respect—It's easy for us to think, "What were they thinking? How could they have treated the Aborigines that way?" But in every generation there's a tendency to treat people as subhuman and therefore expendable. (2) Racism—It's also a powerful story of racism, or how one group devalues and then dehumanizes another group. (3) Justice for the poor and oppressed.