First of all, it would be entirely subjective - ask a white supremist of his values and how ardently that he believes it, and you tell me how to impress upon him that he's wrong?
Indeed, or a theists who has learned to believe and espouses vile and pernicious homophobia, and is just as strident and intransigent in their hatred and prejudice as any white supremacist is in theirs.
Secondly, you take for granted the repulsion that you feel when a heinous crime is committed. There is no other animal on earth besides man that cringes seeing another creature eaten alive, or being dismembered by a vindictive or possessive enemy.
That is pure assumption, you have no clue what other sentient animals may experience.
Animals do not mourn the loss of their offspring or other members of their family (exceptions do not make the rule)
That is entirely incorrect, you have gone from sweeping unevidenced assertions, to asserting errant nonsense.
You take for granted human's sense of compassion and justice, it's innate and not derived by intellect, for even the non-human creatures have intellect.
Where to start with this, firstly all animals that evolved to live in societal groups exhibit empathy, it is an essential trait. Secondly human concepts of justice are subjective, and necessarily derived from our evolved intellect, but obviously our moral precursors are as with other animals, a derivation of evolving to live in societal groups. You also seem to have gone from stridently dismissing non-human animals ability to empathise and experience loss or death, to assigning them an intellect? Seemingly without seeing the paradox.
Without a divine being who has established right from wrong, the holy from the profane, the truth from perversion,
There is no evidence for this assumption, and a cynic might note that this divine diktat seems in every single instance to mirror the ignorance and prejudice of the human culture's and epochs from which they originate. Sadly religious indoctrination then teaches people to cling doggedly to hateful and pernicious ideas, such as the vile homophobia you have espoused on here, for example.
a being that came from protoplasm or stardust would never contemplate or fathom such principles as love, justice, mercy and compassion.
Again pure assumption, and again we can see examples of humans who have evolved like all other living thngs, and yet contemplate just such emotions and principles, and not just human animals either.
The mantra, as all other creatures hold, would be 'kill, or be killed', 'looking out for #1', dog-eat-dog', etc....
It's not a mantra, and the idea other animals hold mantras is pretty ironic and incongruous alongside your other sweeping assertions about them. Nature has evolved animals that are carnivores, this includes humans, even that are on occasion cannibalistic, and again that includes humans.
Humans also evolved big brains, as problem solving gave a massive survival advantage, the agricultural and then industrial revolution have allowed humans time to contemplate their behaviour, freeing them from the constant need to find food and shelter, and so our morals evolve, but this does not require any deity or anything supernatural to explain it, nor are such things objectively evidenced beyond human imagination.
