Christians in the first couple of centuries of the Roman Empire lived longer and were less likely to die than pagans.

The finding

What the evidence shows

This is also Stark's thesis, that Christian charity during plagues in 165 and 251 CE lowered Christian death rates compared to pagans. It is a plausible and influential idea, and later computer modeling found it consistent with theory, but there is no direct ancient mortality data proving Christians actually survived plagues at higher rates, and some ancient Christian writers themselves undercut the picture. Stating it as a plain fact rather than a debated hypothesis overstates what is actually known.