I have visited the Roman Colosseum twice, and both times I stood there, looking out at the arena, and wondered how on earth could anyone have ever sat there and watched another human being be eaten alive, drug behind bulls, sat on fire, etc. How could that be possible for the citizens of Rome? How could a culture that was so advanced, in engineering and architecture,with its Senate which supposedly spike for the citizens, tolerate such a thing? The only answer I could come up with was that before Christ, life had no intrinsic meaning or worth. So, it did not bother most spectators to watch such savagery because they did not consider the victims’ own humanity at all, or couldn’t have tolerated it. Christianity did indeed make us more humanized and compassionate towards our fellow man. In places devoid of Christian sympathy today, you still see this disregard for the preciousness of human life, every human life, born or unborn.
The Romans had no qualms about infanticide either, and it was common for unwanted infants to be left on the streets, to die of exposure. Early Christians took in these infants and nourished them, as they did for the many, many widows whose husbands died in the constant Roman military campaigns.
I have always found that hard to understand. The Roman civilization is one of the most impressive in history, yet they could be incredibly cold-blooded. Tom Holland's book Dynasty calls the Romans the "children of the wolf". Romulus & Remus were allegedly suckled by the she-wolf, and Holland suggests that even though that story is a myth, there was something of the ruthlessness of the wolf in the Romans.