One needs only to search the internet today to determine that there is great controversy and disagreement over the question of whether Jesus of Nazareth was actually Jewish. Before we can answer this question adequately, we must first ask another question: who (or what) is a Jew? Even this question has its controversial elements, and the answer depends on who is answering. But one definition that each of the major sects of Judaism— Orthodox, Conservative, and Reform—would probably agree to is, “A Jew is any person whose mother was a Jew or any person who has gone through the formal process of conversion to Judaism.”
Although the Hebrew Bible does not specifically state anywhere that matrilineal descent should be used, modern rabbinical Judaism believes that there are several passages in the Torah where this is understood or implied, such as Deuteronomy 7:1-5; Leviticus 24:10; and Ezra 10:2-3. Then there are several examples in Scripture of Gentiles converting to Judaism (i.e., Ruth, the Moabitess; see Ruth 1:16 where Ruth voices her desire to convert) and are considered every bit as Jewish as an ethnic Jew.
So, let’s consider these three questions: Was Jesus a Jew ethnically? Was Jesus an observant Jew religiously? And then finally, if Jesus was a Jew, why don’t Christians follow Judaism?
Was Jesus a Jew ethnically, or was his mother a Jew? Jesus clearly identified with the Jews of His day, His physical people and tribe, and their religion (although correcting its errors).. God purposely sent Him to Judah: “He came to His own [Judah], and His own [Judah] did not receive Him. But as many [Jews] as received Him, to them He gave the right to become children of God, to those who believe in His name... (John 1:11-12 NKJV), and He clearly said, "You [Gentiles] worship what you do not know; we [Jews] know what we [Jews] worship, for salvation is of the Jews” (John 4:22).
The very first verse of the New Testament clearly proclaims the Jewish ethnicity of Jesus. “The book of the genealogy of Jesus Christ, the son of David, the son of Abraham” (Matthew 1:1). It is evident from passages like Hebrews 7:14, “For it is clear that our Lord descended from Judah,” that Jesus descended from the tribe of Judah, from which we get the name “Jew.” And what about Mary, the mother of Jesus? In the genealogy in Luke chapter 3, we see clearly that Mary was a direct descendant of King David which gave Jesus the legal right to ascend the Jewish throne as well as establishing without any doubt that Jesus was a Jew ethnically.
Was Jesus an observant Jew religiously? Both of Jesus' parents had “done everything required by the Law of the Lord” (Luke 2:39). His aunt and uncle, Zechariah and Elizabeth, were also Torah-observant Jews (Luke 1:6), so we can see that probably the whole family took their Jewish faith very seriously.
In the Sermon on the Mount (Matthew 5–7), Jesus continually affirmed the authority of the Torah and the Prophets (Matthew 5:17) even in the Kingdom of Heaven (Matthew 5:19-20). He regularly attended synagogue (Luke 4:16), and His teaching was respected by the other Jews of His day (Luke 4:15). He taught in the Jewish Temple in Jerusalem (Luke 21:37), and if He were not a Jew, His going into that part of the Temple would simply not have been allowed (Acts 21:28-30).
Jesus also displayed the outward signs of being an observant Jew. He wore tzitzit (tassles) on His clothing (Luke 8:43; Matthew 14:36) to serve as a reminder of the commandments (Numbers 15:37-39). He observed Passover (John 2:13) and went up to Jerusalem (Deuteronomy 16:16) on this very important Jewish pilgrimage feast day. He observed Succoth, or the feast of tabernacles (John 7:2, 10) and went up to Jerusalem (John 7:14) as required in the Torah. He also observed Hanukah, the festival of lights (John 10:22) and probably Rosh Hashanah, the feast of trumpets (John 5:1), going up to Jerusalem on both those occasions as well, even though it isn't commanded in the Torah. Clearly, Jesus identified Himself as a Jew (John 4:22) and as King of the Jews (Mark 15:2). From His birth to His last Passover Seder (Luke 22:14-15), Jesus lived as an observant Jew.
So, if Jesus was a Jew, why is it that Christians don’t follow Judaism? The Laws of Judaism were given to Moses for the children of Israel in a very sacred and special covenant at Mount Sinai and recorded for us in the book of Exodus. In this covenant, God wrote His laws on tablets of stone, and Israel was commanded to be obedient to all that was revealed to them. But this wonderful covenant was only a picture of a New and better covenant that God would one day give to His people, both Jew and Gentile.
This new covenant is recorded for us in Jeremiah 31:31-34, “‘The time is coming,’ declares the LORD, ‘when I will make a new covenant with the house of Israel and with the house of Judah. It will not be like the covenant I made with their forefathers when I took them by the hand to lead them out of Egypt, because they broke my covenant, though I was a husband to them,’ declares the LORD. ‘This is the covenant I will make with the house of Israel after that time,’ declares the LORD. ‘I will put my law in their minds and write it on their hearts. I will be their God, and they will be my people. No longer will a man teach his neighbor, or a man his brother, saying, “Know the LORD,” because they will all know me, from the least of them to the greatest,’ declares the LORD. ‘For I will forgive their wickedness and will remember their sins no more.’”
Christians don’t follow Judaism today because the Mosaic covenant has been fulfilled in Jesus Christ. Jesus said, “Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them” (Matthew 5:17). And the writer to the Hebrews wrote, “By calling this covenant ‘new,’ he has made the first one obsolete; and what is obsolete and aging will soon disappear” (Hebrews 8:13).
As Christians we don’t need to follow the old covenant any longer because that old covenant has been replaced. We now have a better covenant, with a better sacrifice, administered by a better High Priest! “Therefore, brothers, since we have confidence to enter the Most Holy Place by the blood of Jesus, by a new and living way opened for us through the curtain, that is, his body, and since we have a great priest over the house of God, let us draw near to God with a sincere heart in full assurance of faith, having our hearts sprinkled to cleanse us from a guilty conscience and having our bodies washed with pure water. Let us hold unswervingly to the hope we profess, for he who promised is faithful” (Hebrews 10:19-23).