Historian Rodney Stark writes in The Triumph of Christianity about the significant contrast Christian mercy and compassion was in comparison to pagan religions. Before this passage quoted here, Stark gives the details of the truly horrible conditions in the ancient world. It's worth reading to get a better picture of the terrible conditions Christian mercy intervened to change.
In the midst of the squalor, misery, illness, and anonymity of ancient cities, Christianity provided an island of mercy and security.
Foremost was the Christian duty to alleviate want and suffering. It started with Jesus: “for I was hungry and you gave me food, I was thirsty and you gave me drink, I was a stranger and you welcomed me, I was naked and you clothed me. I was sick and you visited me, I was in prison and you came to me…Truly, I say to you, as you did it to one of the least of these my brethren, you did it to me” (Matt. 25:35-40).
James 2:15-17 expresses a similar idea….In contrast, in the pagan world, and especially among the philosophers, mercy was regarded as a character defect and pity as a pathological emotion: because mercy involves providing unearned help or relief, it is contrary to justice. As E.A. Judge explained, classical philosophers taught that “mercy” indeed is not governed by reason at all,” and humans must learn “to curb the impulse”; “the cry of the undeserving for mercy” must go “unanswered.” Judge continued: “Pity was a defect of character unworthy of the wise and excusable only in those who have not yet grown up.”
This was the moral climate in which Christianity taught that mercy is one of the primary virtues – that a merciful God requires humans to be merciful. Moreover, the corollary that because God loves humanity, Christians may not please God unless they love one another was even more incompatible with pagan convictions. But the truly revolutionary principle was that Christian love and charity must extend beyond the boundaries of family and even those of faith, to all in need. As Cyprian, the martyred third-century bishop of Carthage explained, “there is nothing remarkable in cherishing merely our own people with the due attentions of love….Thus the good was done to all men, not merely to the household of faith.”
It wasn’t just talk. In 251 the bishop of Rome wrote a letter to the bishop of Antioch in which he mentioned that the Roman congregation was supporting fifteen hundred widows and distressed persons. This was not unusual. In about the year 98 CE, Ignatius, bishop of Antioch, advised Polycarp, the bishop of Smyrna, to be sure to provide special support for widows. As the distinguished Paul Johnson put it: “The Christians…ran a miniature welfare state in an empire which for the most part lacked social services.”…
These charitable activities were possible only because Christianity generated congregations, a true community of believers who built their lives around their religious affiliation….Even if they were newcomers, they were not strangers, but brothers and sisters in Christ. When calamities struck, there were people who cared – in fact, there were people having the distinct responsibility to care! All congregations had deacons whose primary job was the support of the sick, infirm, poor, and disabled.