Our ability for abstract thought, allied with empathy. The concepts of fairness, right and wrong are easy to understand to creatures with the ability to think in the abstract, as are understanding when things are generally right or wrong.Rape is part on the natural process and there is no right and wrong about rape in the animal kingdom which would include humans by your metric. The fact you believe it is wrong means you have a moral compass. It makes humans distinct from animals. What is the source of that moral compass?
Math's, the idea of truth etc are concepts that couldn't be any other way than the way they are. For example, the idea of the number one can only be what it is, a representative of a single object or value. If we have two objects, we can't call that pair one because it doesn't fit the defined idea of one. It's the same sort of thing for the idea of right and wrong.Are you programmed by some outside source or is it simply the result of activity in your brain? There is historical precedent for rape as spoils of war which was legal. Rape was part of slavery since the male owned either females or boys who existed for the sexual gratification of their masters. All legal. Still happens today.
There needs to be an explanation, a source. Why is it there in the first place? Do math equations transcend space, time and matter? What about truth? Transcend space time and matter? That would mean things, concepts exist extrinsic of space time and matter which would beg the question, what else exists outside of space time and matter? How about an objective multiplication giver, a moral programmer for humans? If you have a better explanation, we are all ears.
Rape is wrong because of the harm it causes, no matter what selfish man might legislate for.Believe is subjective and i gave you the Rachel Levine example which was cut out. Why should we all be compelled to go along with it at all times in all places? What is the penalty if we do not if legal? If we are to understand your position, you are supposing rape is wrong under a Godless model even if legalized by human rulers. The contradiction here would be in your head and not in your Godless reality. If rape is legal why would your beliefs about rape transcend the rule of men? It would not. You are assuming facts not in evidence nor have you made a case.