And by judging the consequences of that action via our own subjective understanding of morality, we can declare that act to be evil. If our understanding coincides with society’s accepted consensus, we may even declare it a crime, and see that the perpetrator is punished or rehabilitated.
The societal consensus disagrees. We’ve agreed that committing genocide is wrong, and a crime against humanity. Enjoy staring at the wall of a cell at Spandau for the rest of your life.