By the time Constantine declared himself a Christian in 313 CE, almost half of the Roman population had abandoned the traditional Roman gods for Christianity (Galloway 4). The reason for the spread of this particular religion was because the ideas behind it were simple and easy for the people of the Roman world to embrace.
Christian rituals offered equality to its members (Renan 239).
Upper and lower classes as well as slaves and women were able to participate together. This was a welcome change from the Roman way of things for many. In Roman religion, women had no part in any of the ceremonies. They led primarily unreligious lives. Christianity offered these women the chance to stand on higher ground than non-Christian women. Christianity was also appealing to women because there was an important female figure that they could relate to. The Virgin Mary symbolized the importance of motherhood. In the Roman religion it was hard for women to relate to any of the gods.
To many of the people living in Rome at the time, Christianity made sense. It told people that it was their duty to be kind to their fellow man. It also provided protection for the members in that if one were in a bad situation, the others were expected to help him or her out (Galloway 4). Christians at that time believed that the end of the world was at hand and anyone who did not have faith in Christ would encounter the wrath of God. Many people joined the religion because they did not want to take the chance of the Christians being right and being punished for not believing (Gibbon 220).
It was easy to become a Christian. Unlike Judaism where there were many laws and duties to be followed, Christianity was orthodox. One merely had to have faith and one could consider him or herself a Christian. This made the conversion to Christianity an easy one (Class 11/19)
Because Christianity spread so much in Rome, it flowed to every other part of the world. Christianity can be found almost everywhere. The portablity and convenience of being a Christian is a major reason for it dispersing into so many places.