Many rabbis insisted that Ruth, and perhaps even Orpah, converted to Judaism, although the rabbis did not agree on when this occurred. There are good reasons to think that the concept of conversion did not exist during the time of Ruth and was only introduced into Judaism around 125 BCE. Until then, the Israelites thought of themselves as a nation, not a religion. People could join the Israelite nation simply by marrying an Israelite or deciding to be an Israelite and live with the nation. It was much like the naturalization process today, except far easier; there was no paperwork or legal requirements.
It is reasonably certain that conversion did not exist during the time of Ruth. The following supports this conclusion:
- The Torah does not call the Israelites a religion. In fact, the Bible contains no word for religion. Israel is a nation obligated to do what God commands. There is no procedure mentioned in Scripture for joining the Israelites. The concept of conversion, so important to Judaism today, is not mentioned. If it existed, the Torah would have said so.
- There is no reference to a convert in the Hebrew Bible. The word used today for a convert, ger, means “stranger” in the Bible. When Scripture states that the Israelites were gerim in Egypt (the plural form), it did not mean that they were converts but strangers in Egypt. The term appears thirty-six times in the Torah, teaching Israelites to treat non-Israelites well. When the idea of converts was established, the rabbis wanted to emphasize that Jews should treat converts well, just as they treat Jews who were born Jewish. Since the Torah repeatedly emphasizes that the Israelites should love the ger, “stranger,” the rabbis decided to use ger to mean “convert”: one should love converts.
- The term prosēlytos is used in the third-century BCE Greek translation of the Hebrew Bible, called the Septuagint, as the translation of ger. The meaning of the Greek word is “stranger,” as is the Hebrew word, and it is only later that it came into the English language to signify a proselyte, a person who converted to another religion.
- Many important Israelites married non-Israelites and the Torah never says that the women had to undergo conversion or any procedure. For example, the patriarch Abraham married Keturah, Judah the son of the patriarch Jacob married a Canaanite, his brother Joseph and Moses married daughters of pagan priests, the judge Samson married a Philistine, and King David and King Solomon had wives from many nations.
- Genesis 12:5 states that Abram and Sarai took with them “the nefesh they had gotten in Haran.” Genesis Rabbah 39:14 and 84:4 and the Babylonian Talmud, Sanhedrin99b, interpret the phrase as a reference to converts; however, this interpretation is sermonic. The term nefesh is translated today as “soul,” but it means “person” in the Torah, so the verse is saying that the couple took along the people (slaves) they had acquired in Haran.
- Some rabbis misinterpreted Deuteronomy 17:15, which states: “One from among your bothers shall you set as king over you, you may not put a foreigner over you who is not your brother.” They understood the command to exclude converts from serving as a king in Israel. Actually, Deuteronomy 17:15 does not mention a convert, but a foreigner. A convert is a person who ceases being a foreigner and becomes a full-fledged Jew. The Torah means what it says. Verse 17:14 speaks about the entry of the Israelites into Canaan. In verse 15 the Israelites are told that they should not appoint a foreigner, meaning a Canaanite or any other foreigner, as their king. This rule is reasonable. In verse 18, the Torah instructs the king to follow the Torah laws. Thus, the purpose for excluding a non-Israelite was to assure that the people would observe the divine laws and not worship idols. Having a foreign king with his own agenda would frustrate the divine plan. Furthermore, the word “foreigner” is an inappropriate if not insulting description of a person who voluntarily converted to Judaism.
- Mishnah Sota 7:8 supports the view that the sages felt that a convert and a descendant of a convert may serve as a king of Israel. It reports that King Agrippas (c. 10 BCE–44 CE) was a descendant of Herod, whose ancestor was one of the first people converted to Judaism by John Hyrcanus. Agrippas, relates the Mishnah, was crying because he understood that Deuteronomy 17:15 made him ineligible to serve as king. But the sages replied emphatically: “Fear not, Agrippas! Thou art our brother! Thou art our brother! Thou art our brother!”
- Some people argue that Moses’s father-in-law Jethro converted to Judaism. They draw on Exodus 18:10–12, which narrates that Jethro was impressed with all that God did and offered sacrifices to God. However, this narrative proves nothing. It does not state that Jethro converted; it doesn’t even say he gave up his pagan priesthood and joined the Israelites. Jews always accepted sacrifices from pagans without the pagans needing to accept the Lord as their sole God. Additionally, Jethro seemingly does not reject the existence of other gods; he says “the Lord is greater than all gods.”
- There is no explicit statement in Ruth that she or her sister-in-law Orpah converted, and even the rabbis who feel they or at least Ruth converted differ on how to read the text. Rashi felt that only Ruth converted and did so during the trip to Judea. Ibn Ezra opined that both converted prior to their marriage to Mahlon and Chilion.
- The book of Ruth not only does not indicate that Ruth converted, it states seven times that she remained a Moabite – including twice in the final chapter, where Boaz calls her a Moabite when he speaks about marrying her. The number seven is significant since Scripture very frequently mentions something seven times to emphasize a point. The number seven is repeated in 4:15 when the people say that Ruth is better for Naomi than seven sons; the city of Bethlehem appears seven times, as does the field of Moab and the words el and natan. This repeated use of seven emphasizes that we should pay attention to this number in Ruth.
- In 2:10, Ruth calls herself a nokhria, a “foreigner,” in a conversation with Boaz. If she had converted she would not be a foreigner.
- Some rabbis base their notion that Ruth converted on her statement to Naomi, “Your God is my God.” Reciting these words alone was never considered efficacious in making a person a convert. A ceremony of some sort was probably necessary. There is no ceremony here and significantly, Naomi does not say to Ruth, “Now you are a Jew.” Even more significant, Ruth does not declare that she will obey Torah laws. Ruth Rabba and other Midrashim recognize this lacuna and declare that she did promise to obey the Torah laws, but this is not recorded in the book of Ruth.
- What was Ruth saying when she said “Your God is my God”? She was responding to what Naomi had said: “Look, your sister-in-law returned to her people and her god; you should return after your sister-in-law.” Ruth answered: “No, I will go where you go and your God will be my God.”
- Additionally, many ancients, and apparently also Ruth, believed that each nation had its own god who protected his or her own land. Ruth’s statement “Your God is my God” was another way of saying, “Your land will be my land.”
- Ezra and Nehemiah felt very strongly that the Judeans should not be married to non-Judeans. As leaders of the people at that time, they ordered Judeans to send away their non-Judean wives and children. This draconian measure would not have been necessary if conversion existed.
- The first mention of conversion is when the Hasmonean king John Hyrcanus forcibly converted Edomites around 125 BCE.
 The Hebrew word used today for religion, dat, means “law” in the Bible, not religion.
 Genesis 25:1. One can also add the non-Israelite concubines, such as Abraham’s concubine Hagar and Jacob’s two concubines, Bihah and Zilpah.
 Genesis 38.
 Mentioned in the midst of a legend in the Babylonian Talmud, Bava Batra 3b.
 William Whiston, trans., Antiquities 8:1, in The Life and Works of Flavius Josephus (Philadelphia: John Winston, 1957). Because these conversions were forced, and since King Herod was born from these people, some Judeans never accepted Herod and his descendants as Jews. This reluctance by some Jews to consider the Herodians as proper kings may have been because of the force used to make them Jews, not because they were converts.
 It appears that no formal ceremony existed for the acceptance of a proselyte until the second century CE. There were still discussions at that time whether circumcision was necessary (Babylonian Talmud, Yevamot 46a). However, even if no formal ceremony existed, we would expect at least an informal one.
 Nachmanides, for example, was convinced that God only exercises divine power in Israel (see Charles Ber Chavel, ed., Sefer Hamitzvot l’Harambam im Hasagot Haramban [Jerusalem: Mossad Harav Kook, 1981], 359): “There is in this matter a secret relating to that which the rabbis have said: ‘He who dwells outside of the land of Israel is like one who has no God.’” Nachmanides understood that the Talmud is stating that people who live outside of Israel are under the influence and power of these other supernatural beings and even if they try to worship God it is as if they have no God.
 See Ezra 9 and Nehemiah 13.
 Nehemiah tells us that he fought with the men who married non-Judeans, cursed them, smote them, and plucked out their hair. He wrote that Solomon whom God loved sinned in this way. This point is made by Y. Kaufman and is quoted by Klein in Megillot, Olam Hatanakh (Divrei Hayamim, 1999).
 Whiston, Antiquities 8:1, in The Life and Works of Flavius Josephus, 394.