Christianity originated in the first century AD, apparently from the teachings of Jesus Christ. According to Acts 11:19 and 11:26 in the Christian New Testament, Christ's followers were first called Christians by non-Christians in the city of Antioch, where they had fled and settled after early persecutions in Palestine. After Jesus' death, early Christian doctrine was established by Paul of Tarsus.
Relative peace and good roads throughout the Roman Empire allowed Christianity to spread quickly over the next three centuries, but more important was the conversion of Emperor Constantine in 312. Combined with his Edict of Milan in 313, Constantine's conversion effectively made Christianity the favored religion of the Empire, and he organized the first of several ecumenical councils for resolving doctrinal issues. Between about 410 and 1050, missionaries from Constantinople, Ireland (from about 450), and elsewhere evangelized Christianity throughout Europe, translating the Bible into local languages and sometimes incorporating elements of native culture into Christian custom (see for example Easter: Symbolism of Easter, Halloween: Christianizing the Celtic Samhain).
1 -[Christianity : Origin & culture]
2 -[Christianity : History of Christianity]
3 -[Christianity : Christian Doctrine]