The Elevation of Human Dignity
Children - We forget that in the ancient world, child sacrifice was fairly commonplace. Rome is held up as the great place of learning, but it was also a place of rampant infanticide. Some children were offered up to gods, some children were killed because they were deformed and/or female. I won't get into the various methods of child abandonment and killing here.
When Jesus came he elevated the value of children, teaching that the kingdom of God belongs to such as them. His Gospel led to James saying that "pure and faultless religion is to take care of widows and orphans." Foundling homes, orphanages, and nursery homes were started in this time. Abortion, abandonment, and infanticide began to disappear in the time of the early church. These practices helped create a foundation in Western civilization for an ethic of human life. Even today, the front lines of the pro-life fight for valuing babies is full of Christians.