If you are Jewish, you remain Jewish, always, no matter what!
According to the Orthodox, a Jewish person is any person whose birth mother was a Jew, or any person who has gone through the formal process of conversion to Judaism. A person born to non-Jewish parents who has not undergone the formal process of conversion, but who believes everything that Orthodox Jews believe, and observes every law and custom of Judaism, is still a non-Jew, even in the eyes of the most liberal movements of Judaism.
And a person born to a Jewish mother who is an atheist and never practices the Jewish religion, is still a Jew, even in the eyes of the ultra-Orthodox. In this sense, Judaism is more like a nationality than like other religions, and being Jewish is like a citizenship (Reference.) This reference even says that it is important to note that being a Jew has nothing to do with what you believe or what you do.
Given that information, then the reality is that a person who is born a Jew can believe in and practice whatever they want, their identity as a Jew is not something that can be taken away from them. A fascinating post on the Chabad website testifies to just that: “Jewishness is not a belief, a feeling, a conviction or a lifestyle. It is a state of being. We can either celebrate it or fight against it. But it will always be there.”
I Kings 18:21 says “And Elijah drew near to all the people and said, Until when are you hopping between two ideas? If the Lord is God, go after Him, and if the Baal, go after him. And the people did not answer him a word.” Elijah the prophet was sent to rebuke those Jews who were worshiping a foreign god named Baal. The people were given a choice, if the Lord is God, follow Him, but if Baal, follow him. Ultimately the Jews renounced their idolatrous ways and returned to God.
Some have concluded that this is saying that a Jew who follows another religion is Jewish only to the point that he retains a spiritual obligation to repent and return to Judaism. Following that line of reasoning, as long as a Jew’s beliefs are idolatrous and foreign to Judaism, he/she cannot call himself or herself a Jew. In that same analysis some have made the differentiation between a non practicing Jew and one who has chosen to follow a “foreign” path (Pages 18-19 “The Jewish Response to Missionaries – Counter Missionary Handbook” by Rabbi Bentzion Kravitz.)
Is this what the Tanakh truly says? We must carefully consider the context of passages. In other words, we must look carefully at verses that precede and that follow a verse we are studying. When we take a passage “out of context” we are in danger of misinterpreting it. A passage can often be taken more than one way, until we look closely at the larger picture, perhaps an entire chapter or even the entire book.
Does it say in I Kings 18 that those who followed Baal were no longer Jews? No. Verse 18 “And he said, “I have not brought trouble upon Israel, but you and your father’s house, since you have forsaken the commandments of the Lord, and you went after the Baalim.” There is absolutely no mention of a loss of identity; what there is mention of is there were consequences from God, trouble, just like when we forsake God and pursue ungodly activities and interests. When we turn from God and follow our own path, there most certainly are consequences; natural ones as well as one’s from God.
Some may say that the Torah teaches that Jews and non Jews are given different paths to reach God. A Jew is obligated to follow the Torah while a non Jew must observe the Seven Laws of the Children of Noah. (Page 19 “The Jewish Response to Missionaries – Counter Missionary Handbook” by Rabbi Bentzion Kravitz.) That is found absolutely nowhere in the Tanakh. That is a Rabbinical thought expressed in the Oral Torah inferred from Genesis 9.
Now getting down to what the Bible actually states. The Tanakh does not specifically state anywhere that matrilineal descent should be used. The Orthodox Jews are using the following to support the matrilineal descent theory: Deuteronomy 7:1-5, Leviticus 24:10 and Ezra 10:2-3. Source.
However taking into account the context of these scriptures within the rest of the Bible, those scriptures discuss the intermarriage between a believer; a follower of God, and a non believer or a non follower of God like Deuteronomy 22:10, 1 Corinthians 5:9, 2 Corinthians 6:14-17 state.
Regarding who is a Jew, the Tanakh states that a Jewish person is any person who is a descendant of Israel (Jacob), as well as the patriarchs Abraham and Isaac, and their wives. (Genesis 12:1-3, Psalm 77:16 [Psalm 77:15 OT].) Interesting too, according to the Tanakh there isn’t any set out list of requirements to formally convert to Judaism. Ruth is held up by all as an example of conversion (Ruth 1:16.)
Who is a Gentile?
Gentiles are people who are not Jewish. Gentiles are not born Christian either. No one is BORN a Christian or is a Christian simply because their parents are Christians or they were sprinkled with water at an infant baptism. There is a personal and inner decision that each INDIVIDUAL must make for him or herself in order to become a Christian. Gentiles who place their faith in Jesus are “grafted into” the Jewish olive tree of faith Romans 11:17-25 becoming spiritual sons and daughters of Abraham (Galatians 3:28-29.)
Who is a Christian?
Anyone, GENTILE OR JEW, who receives Jesus as their Savior (Romans 10:11-13.) One is not born a Christian the way one is born a Jew or born a man (XY Sex Chromosomes) or a woman (XX Sex Chromosomes.) One is also not baptized into becoming a Christian either the way one might be baptized into a religion for example as in infant baptism by sprinkling of water. To become a Christian as the Bible states it, one must actually decide that they believe what scripture says about receiving salvation.
Bringing this page together regarding Jewish people….
If a Jewish person has decided for him or herself that Jesus is indeed the Messiah and has received Jesus as such, then they have a dual identity as Jewish and as a follower of Jesus.