Early Christianity: This is the most common and neutral term. It simply refers to the period of Christianity's development from its beginnings in the 1st century CE to the 4th century CE.
Primitive Christianity: This term emphasizes the "original" form of Christianity, before it became the dominant religion of the Roman Empire.
Apostolic Age: This term focuses on the period immediately following the death of Jesus, when the apostles were actively spreading the Christian message.
Emergent Christianity: This term is more modern and emphasizes the dynamic and evolving nature of Christianity during its early stages.
The Way: This was the original name used by early Christians to describe their movement, as seen in the New Testament (Acts 9:2, 19:9, 22:4, 24:14). It signified their commitment to following Jesus' teachings and example.
Ultimately, the best term to use will depend on the specific context and what aspect of the early Christian movement you want to highlight.