Chrisiatnity was not easily or quickly accepted in ancient Rome. The first Christian converts faced a lot of discrimination. They were at times persecuted, and could even face death.
However, over time, Christianity led to many changes in the Roman Empire. In 313 CE, the Edict of Milan was issued by Emperor Constantine. This granted legal status to Christianity, as well as other religions. This was an important change in Rome as it opened the door to religious tolerance. In 325 CE Constantine called the Council of Nicaea to determine the beliefs of Christians, leading to the Nicene Creed. Eventually, in 380 CE, the Edict of Thessalonica made Christianity the official religion of the Empire, with an enormous impact on the culture and religion of Rome.