1. Social Networks : Again and again, research shows that religious conversions happen “…through social networks, through a structure of direct and intimate interpersonal attachments.” Everyday friendships and the personal interactions of average believers are what makes the greatest difference — nowadays and in the past.
2. Caring for the sick, widows, and orphans: Plagues, fires, natural disasters, and devastation from riots or war were semi-regular occurrences in the cities which the early Christians called home. What distinguished Christians was their response to these all-too-frequent calamities. Instead of fleeing to the countryside to escape the most recent plague, they stayed to care for their own — and for others. Even without any knowledge of medical science , the simple act of providing food, water, and shelter to sick people vastly improved survival rates in times of widespread disease. It also sent a powerful message of solidarity to those pagans who happened to receive a helping hand. The results, over time, were shifting social networks and regular conversions to this community of faith so dedicated to service.
3. Stance against adultery, abortion, and infanticide: The ancient Roman world was not kind to women and children. Married men could sleep with other women (especially slaves and prostitutes), and the unwanted offspring of these unions were usually aborted or simply left to die from exposure after birth. Christians spoke out against all of these practices, exhorting the followers of Jesus to remain faithful in marriage (even the men!), and to care for the most vulnerable members of society: little babies. Some Christians would even rescue abandoned babies, raising them as their own. All of these beliefs and actions led to higher birth and adoption rates.
4. A Theology of Love: The actions described above — engaging one’s neighbor, caring for the sick, rescuing little babies — reflect certain Christian theological principles. The most important one is the insistence that God loves the world He has created and that He desires those who love Him to also love their fellow man. In our post-Christian context, such an idea seems self-evident. It’s almost a cliché. Yet an all-encompassing ethic of love is a radical idea. We believe in it so widely nowadays, at least on a theoretical level, only because Christianity incorporated it so successfully into the very being of Western civilization over centuries. In The Rise of Christianity, Stark does the math, and shows that a social movement numbering only 1,000 people in 40 A.D. could easily grow to 25 or even 35 million by the fourth century, despite all of the challenges of the ancient world — if the members of the movement lived according to the principles spelled out above. Doing so leads to very tangible demographic results: 40% growth per decade for hundreds of years.
What are we to do with this information? First of all, we must set aside the pietistic belief that Christianity’s early growth happened entirely because of miracles — the signs and wonders wrought by a special out-pouring of the Holy Spirit. Certainly, the providence and grace of God is always an essential factor. Yet a full look at the evidence reveals that much more was at play. Ignoring the other contributing factors has the unfortunate consequence of breeding complacency: if modern Christians think that the early Church’s growth was “merely” miraculous, then there’s little to learn and nothing to do. We are left with prayer and hope, but no concrete action. Research like Stark’s provides an unmistakable and powerful lesson: the regular witness of ordinary, every-day Christian people tending to the poor, the orphans, and the sick in their own urban communities contributed decisively to early Christianity’s tremendous growth. If we, as modern Christians, want similar results, we must act in the same manner. To be faithful to God’s self-revelation in Jesus Christ requires more than coming to Church; it also entails being the Church — that body of God’s adopted children called to manifest His love in the world.