Judeo-Christian values are the basis of the west's moral code. It's so ingrained you may think it's innate. But it's not hard to impress a different set of values if you preach them from birth. People years ago who believed in racial prejudice were not born bad. They believe what they were taught by society. Some were able to overcome this teaching but for the vast majority they just considered these beliefs as facts. That's why its ridiculous to judge a historic figure based on our current moral code.