None of the Romans believed in the moral equality of all human life. They believed just the opposite. It was taken for granted by the Romans that some lives were more valuable than others, that some lives were to be preserved at the cost of other lives. The same view prevailed among the ancient Greeks also. You would look in vain to find a Roman or Greek of any stature who would dare to suggest that the life of the unborn or the child or a woman was equal to a man and then only to certain men. All across pagan Europe from the Vandals to the Goths to the Vikings you find a normal and normative belief that lives are not equal nor are they worthy of equal protection. Where do you find this in Islam? People simply believed nothing of the sort until Christianity came along. For Pete's sake, survey the history of China or Japan. Look at the great empires of the Inca or Aztec people -- don't forget that both societies were still practicing human sacrifice when the Spanish arrived about 500 years ago. There is no civilization that would grant all or even most lives protection, value, and worth apart from Christian influence and intervention.
Indeed, the very mark of the undoing of our Christian influences in the West can be seen in the way we no longer as a culture and civilization give any credence to the moral equivalency of life. From abortion to assisted suicide to euthanasia, we live in a time in which life is relative and its status more fragile than it has been since the dawn of Christianity itself. Though the secular world loves to blame Christianity for war, violence, a class system, prejudice, racism, and slavery, these things existed long before Christ was born and were challenged precisely by a Christian worldview. Though secular liberals and progressives daydream of a world without Christianity, the reality of what that world would look like is scary to everyone who is not in the majority or in control. The creed of liberals insists that the protection of rights and the value of life extends to all, try disagreeing with the propagandists of this liberalism and you will see how quickly rights are selectively granted. We see the evidence of this all around us.
The end result of a world in which Christianity is exterminated or silenced is a threat to the value and protection of all life. We may not see it now but it would not take long under the scenario imagined by progressives and liberals before we would see the truth of it all. Christianity is not a danger to the value and protection of life but its savior.