In What Does the Bible Say About..Why Jews Don't Accept Jesus you said: "Although there were only Jewish Christians for approximately ten years after Jesus died, non-Jewish (Gentile) Christians have become the majority."
If Jewish is just a religion, then how could there be "Jewish Christians?" You cannot be two religions at the same time. Judaism and Christianity have totally different teachings. Christianity learns from the Holy Bible, while Judaism is taught out of the Talmud, which is the chief authority of Judaism.
Answer
“Jewish” is not just a religion. It is primarily an ethnicity and only secondarily a religion. One can be Jewish without being religious. One can be born not Jewish and choose to accept the Jewish religion. So the term refers to both the ethnicity and the religion.
For almost ten years everyone who became a Christian had been born Jewish. Most, including the apostles, still retained their belief in the Jewish religion as well. That is because Judaism and Christianity don’t “have totally different teachings.” Christianity, according to the book of Hebrews and some of Paul’s writings (Romans, Ephesians, and Galatians), is the fulfillment of Judaism. The basic doctrines of Christianity come from Judaism. Even some of the basic practices of Christianity (the Lord’s Supper, baptism, the worship assembly, and prayer) come directly from Judaism.
During the first two centuries of the existence of the church there was no written Talmud. There were traditions passed down through the rabbis that were later written down in Talmud. Jesus did speak out against some of these traditions, but never condemned the basics of Judaism. In fact, he kept the Law of Moses perfectly. The apostles continued to follow the Law of Moses in many respects even while they were in the church. We know from Acts 10 and Galatians that Peter continued to keep kosher. Paul observed Passover, and possibly other of the Jewish holidays.
The most significant difference between Judaism and Christianity is in their understanding of the idea of Messiah. The Jews do not accept that Jesus was the promised Messiah. Christians say he was the fulfillment of all the prophecies about Messiah. Beyond that, the differences between the Christianity written about in the Bible and the Judaism of the Bible are minor.
Some sects of modern Judaism do put almost equal emphasis on Talmud as on the Old Testament. Perhaps some may even put more emphasis on the Talmud and more recent traditions. The basis of Judaism, however, remains the Bible.