The disciples of Jesus were first called Christians at Antioch (Acts 12:26). After the Holy Spirit came upon Jesus' disciples at Pentecost, those first Christians bore witness to the risen, resurrected and glorified Christ Jesus as the only way to be saved.
Before Jesus was born, he was the Word of God who was with God in the beginning and who is God. The Word dwelt with man when he condescended to lower himself and take on human form (John 1:1-14). Yes, Jesus, the Word, existed alongside the Father and the Holy Spirit from before creation, from before Abraham was born and before God chose the Hebrew nation as his chosen people.
Jesus was born as a Jew and followed the Jewish religion. He studied the Hebrew Scriptures and was intimately familiar with the Law and Prophets - as well as the hypocrisy of the religious leaders who imposed heavy burdens on God's people. Everything in the Hebrew Scriptures was pointing forward to the coming of the Messiah, the Christ, and everything that happend prior to the coming of Jesus was part of God's divine plan to salvation. But is Judaism the same thing as the religion of the Jews during the time of Jesus?
All I know is that some Jewish Christians tried to Judaize Gentile Christians, and make them live according to Jewish customs. The word 'Judaizer' appears in Galatians 2:14 where Paul challenged Peter for forcing Gentile Christians to “Judaize.” Peter wanted the Gentile converts to live according to Jewish customs and obey the Laws of Moses such as be circumcised, observe the Sabbath and the Passover, and adhere to all the dietary laws, etc. After living in Egypt for about 430 years, God had given the Israelites 613 Laws at Sinai. Some Jewish Christians thought that Gentiles should convert to Judaism in order to be right with God. During the first century, the Christian church was being infiltrated by the Ebionites, who denied the divinity of Christ and the virgin birth and who opposed the Apostle Paul. The Church was also under attack from an early form of Gnosticism, legalism, ascetism and the worship of angels.
In Acts 15 we read of a group called the Judaizers who opposed Paul and Barnabas at the council of Jerusalem in A.D. 50. Those Christians who belonged to the party of the Pharisees (Judaizers) insisted that Gentiles could not be saved unless they were first circumcised and obeyed the Law of Moses. Paul assured them that with God, there was no longer any distinction between Jew and Gentile, for God had purified the hearts of the Gentiles by faith (Acts 15:8-9). Paul made it very clear that salvation is a gift from God to Jews and Gentiles alike and trying to keep all of the Law simply condemns because it is impossible for imperfect people to keep God’s perfect Law.
Read Galatians 2:14-16; 3:10-14; Romans 8:1-4; 9-10. Salvation does not come about by works or by adhering to the Law, but comes through the grace of God. To add anything to the work that Christ did for salvation is to negate God’s grace. “I do not set aside the grace of God, for if righteousness could be gained through the law, Christ died for nothing” (Galatians 2:21).
Christianity is not founded on the Law (Judaism) but on free grace and Jesus is the mediator of a NEW Covenant (Hebrews 12:24). LM