On the feast of Pentecost that followed the crucifixion, Peter and the rest of the apostles were metamorphosed under the influence of the divine Spirit from a group of gutless fugitives into born-again champions of the faith in Jesus, the risen Messiah, and their charismatic proclamation to the Jerusalem crowds instantaneously increased the original nucleus of 120 Jesus followers by 3,000 new Jewish converts. All they were asked to do was to believe in Peter's teaching about Jesus and be baptised in his name. 

The individual members of the Jerusalem Jesus party did not call themselves by any specific name, but their religious movement was known as "the Way" (Acts 9:2; 19:9; 24:14), short for "the Way of God". Only at a later date, after the establishment of a community in Antioch in northern Syria, do we encounter in the Acts of the Apostles 11:26 the specific designation Christianoi ("Christians" or Messianists), applied to the members of that particular church. 

How did the original Judaeo-Christians of Jerusalem compare to their Jewish neighbours? In some essential ways they did not differ from them at all. The Judaeo-Christians considered themselves Jews and their outward behaviour and dietary customs were Jewish. In fact, they faithfully observed all the rules and regulations of the Mosaic Law. In particular, the apostles and their followers continued to frequent the religious centre of Judaism, the Temple of Jerusalem, for private and public worship, and it was there that they performed charismatic healings (Acts 3:1-10; 5:12, 20, 25, 42). According to the Acts, the entire Jesus party assembled for prayer in the sanctuary every day (Acts 2:46). Even Paul, the chief opponent of the obligatory performance of Jewish customs in his churches, turned out to be a temple-goer on his occasional visits to Jerusalem. He once fell into a trance in the course of his prayer in the House of God (Acts 22:17) and on a later occasion he underwent the prescribed purification rituals before commissioning the priests to offer sacrifice on his behalf (Acts 21:24-6). 

In addition to their attachment to the Law of Moses, including worship in the Temple, the religious practice of the first Jewish Christians also included the "breaking of the bread" (Acts 2:46). This breaking of the bread was not a purely symbolical cultic act, but a real meal. It had the double purpose of feeding the participants and symbolically uniting them with one another as well as with their Master Jesus, and with God. The frequency of the rite is not immediately specified, but the initial impression is that it took place daily, not unlike the sacred dinner of the fully initiated Essenes, described by the Jewish writers Philo, Flavius Josephus and the Community Rule of the Dead Sea Scrolls. "And day by day, attending the temple together and breaking bread in their homes, they partook of food with glad and generous heart" (Acts 2:46). On the other hand, according to Acts 20:7, Paul in Troas broke the bread on the first day of the week, and the Didache, the earliest Christian treatise (late first century CE), also orders that the bread should be broken and thanksgiving (Eucharist) performed each Sunday (Did. 14:1).