I'd say a heathen is - from the Amarrian perspective - simply someone who's not embracing the Amarrian religion. A heretic is someone who distorts Amarrian religion. Thus, enemies of Amarr can be heathans as well as heretics - a heretic is in fact by necessity an enemy of Amarr, while the same is not true for a heathen.
I'd agree though: I can't think of rape being considered as something else than being in itself immoral (as it is kind of the type of distortion of Amarrian religously motivated ethics like Sani Sabikism is a distortion of it in general).
As to the 'chosen people':
"Our Lord visited his flock and saw that all was not good.
Blasphemy and heresy ruled the land.
The Lord punished the sinners and drowned them in their own blood.
But the people of Amarr lived righteously and in fear of God.
Thus they were saved and became God's chosen."
- The Scriptures, Book II 2:1
I think the important part here is, really, that God chose the Amarr not because they were Amarr, had a certain genetic trait or blood flowing in their veins: They became His chosen, because they had certain religious and moral qualities. It is these qualities that God seeks in people and he takes those up as his chosen people. Right makes Might (not the other way around: that would be the Sabikist distortion).
Otherwise an Amarrian holder couldn't fall from grace and into slavery, by definition. Amarrians are usually quite aware though, that they are not exempt from the need to behave in a faithful and god-fearing way. Compare the repeated admonishon in ther Scripture's that God is testing the Amarr again and again and they must show that they are deserving of his gifts.