Abstract
Christianity is a complex phenomenon, especially during the initial period. The use of the plural “Christianities” in historiography aims to emphasize this complexity. This paper offers some examples to highlight the different ways of life, the manifold interpretations of Jesus, the diverse organizations of churches and of worship during the first two centuries. The paper goes on to discuss the concept of Christianity and proposes a definition deriving from the impact of Jesus on believers. This impact led to his veneration, whether in an exclusive sense or not, but always in a decisive manner, given that, as the eschatological envoy, Jesus is the cause of salvation.