Judaism is not a missionary faith and so doesn’t actively try to convert non-Jewish people (in many countries anti-Jewish laws prohibited converting to Judaism for centuries). Despite this, the modern Jewish community increasingly welcomes would-be converts. A person who converts to Judaism becomes a Jew is just as Jewish as someone born into Judaism.
There is a good precedent for this. Ruth, the great-great grandmother of King David, was a convert to Judaism, and the book of Ruth in the Bible which tells the story of her becoming Jewish, is read every year during the services held on Shavuot; the celebration of the Jewish People’s receiving the Torah at Mount Sinai.
Although Jews do not send out missionaries, it is a Mitzvah to welcome non-Jews who are interested to study Judaism and to join the Jewish people if they so desire. There are at least eight good reasons for Jews to encourage interested non-Jews to join the Jewish people.
1-“If a (potential) convert comes to convert, one should extend a hand to him (in welcome) to bring him or her under the wings of the Shekhinah” (Vayiqra Rabbah 2:9).
2-Rabbi Shim‘on ben Lakish taught: “A proselyte is dearer to God than was Israel when it was gathered together at Mount Sinai, because Israel would not have received the Torah of God without the miracles of its revelation, whereas the proselyte, without seeing a single miracle, has consecrated himself or herself to God and accepted the kingdom of heaven” (Tanhuma, Lech Lecha, ed. Buber, p. 32a)
3-The central daily prayer of all Orthodox and Conservative Jews includes this all inclusive phrase: “May Your mercies be aroused, Lord our God, upon the righteous, upon the pious, upon the elders of Your people the House of Israel, upon the remnant of their sages, upon the righteous proselytes and upon us (ordinary Jews)”.
4-“Thus says the Lord of hosts; In those days it shall come to pass, that ten people out of every language of the nations, shall take hold of the shirt of one who is a Jew, saying, We will go with you: for we have heard that God is with you.” (Zechariah 8:23).
5-“When a person wants to become part of the Jewish people, we must receive him or her with open hands so as to bring that person under the wings of the Divine Presence” (Leviticus Rabbah 2:9) for “Behold, I am a God who brings near’ says the Lord, “and not a God who repels”.(Jeremiah 23:23)
6-An Israeli Diaspora Affairs Ministry committee said in a statement that more than 50 million non-Jewish people worldwide have an affinity with Judaism or Israel, including both groups and individuals who could be screened for potential conversion and immigration to Israel.
7-In our present society many people are interested in becoming Jewish for many reasons. Being saved by believing in Judaism as the only true religion is not one of them. If you do not have a questioning spirit Judaism is not for you.
8-The Hebrew word for reincarnation is gilgul which means recycling. According to Kabbalah many people are born with new souls who are here for the first time. Others have a soul that has lived on this planet before.
Most people who end up becoming Jewish, especially now, after the Jewish people have experienced several generations of assimilation, marriage to non-Jews, hiding from anti-semitism and outright genocide, are descendants of people whose children, in one way or another, have been cut off from the Jewish People. Among their non-Jewish descendants a few will inherit a Jewish soul that will seek to return to the Jewish people.
If you know any non-Jews who seem very Jewish in their thinking they might have an ancestor who was Jewish. If nobody in their family seems to know, share with them this introspective personality and character test to help find some hints.
1- Do you like to ask questions especially about religion? But when you asked them as a child, you were told faith is a gift from God and you shouldn’t question it. This never satisfied you, although others didn’t question it.
2- The trinity never made any sense to you even as a young child. You prayed to God the father more easily than Jesus, the son of God, even though you were told to pray to Jesus. You never could believe that people who didn’t believe in Jesus couldn’t go to Heaven.
3- On first learning of the Holocaust you reacted more emotionally than your friends or other members of your family. You feel some sense of connection with the Jewish struggle to defend Israel.
4- You have an attraction to Jewish people, or to Judaism and Jewish culture. You have always been more open to people who were culturally, nationally or religiously different from your own family, than your friends or class mates.
If you answer yes to three of these four items you probably have Jewish ancestors. Many, but not all, people who answer yes to all four items will be interested in learning more about their Jewish roots. If you become very interested in studying Judaism you might have a Jewish soul.
According to Jewish mystical teachings (Kabbalah), many (not all) people reincarnate after they die. This is especially true for Jews who died and had no Jewish children who survived them (Sefer HaPliyah). Their souls reincarnate in one of their non-Jewish descendants who is drawn to: Jewish things, Jewish people and Judaism. If the following item also applies to you, you certainly have a Jewish soul.
5- When you start to learn about Judaism: the ideas and values seem reasonable to you; the traditions and heritage are very attractive to you; and the non-Jews around you as well as you yourself, are surprised that you slowly come to feel that you are coming home.