The easy way is to say it was correct back then and not relevant anymore. We've heard Christians justify slavery and genocide as god's anger or something like that, it only takes a bit of mental gymnastics - A Christian friend of mine uses the analogy of someone building a house and in the middle of the process killing lots of bugs accidentally because the person is so big and powerful - That's god and humans
Whoever fights monsters should see to it that in the process he does not become a monster. And if you gaze long enough into an abyss, the abyss will gaze back into you