The truth about conversion
Many rabbis insisted that the biblical Ruth and perhaps even Orpah converted to Judaism. There are good reasons to think that the concept of conversion did not exist at the time and was only introduced into Judaism around 125 BCE. Until that time, the Israelites thought of themselves as a nation not a religion. People could join the 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.
The Torah does not call the Israelites a religion. 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 converts in the Hebrew Bible. The word used today for a convert, ger, means “stranger.” When Scripture states the Israelites were gerim in Egypt (the plural form), it did not mean that they were converts but strangers in Egypt. The term appears 36 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 mentions that the Israelites should love the ger, stranger, thirty-six times, they 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 Septuagint, as the translation of ger. The meaning of the Greek word is “stranger,” as is the Hebrew word, and it only later 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 does not say the women had to undergo conversion or any procedure. Among the many were: the patriarch Abraham who married Keturah, Judah the son of the patriarch Jacob, his brother Joseph and Moses who married daughters of pagan priests, the judge Samson, King David, King Solomon.
The midrashic interpretations of Genesis 12:5 that Abram and Sarai took with them “the souls they had gotten in Haran” means converts 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 acquired in Haran.
The Talmudstates that the prophet Samuel wrote Ruth to show the people of his time that his choice of David to succeed King Saul was proper because despite being descendant from a Moabite, his ancestress was legally permitted to enter the Jewish fold. Whether this statement is true or not, it is significant that if the book was composed to show that Ruth was legally permitted to enter the Jewish fold and if conversion was necessary at the time to be a Judean, the author should have stated that she converted. This would have demonstrated his point better than anything else.
There is no explicit statement in Ruth that 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 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.
Some rabbis base their notion that Ruth converted on her statement to Naomi “your God is my God.” This statement 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.”
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 stating that “your land will be my land.”
Ezra and Nehemiah felt very strongly that the Judeans should not be married to non-Judeans and, as leaders of the people at that time ordered to 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.
 Genesis 25:1. One can also add the concubines among the many non-Israelite women married to famous Israelites. Abraham had Hagar. Jacob had Bilhah and Zilpah.
 Quoted by Rashi.
 Babylonian Talmud, Baba Bathra 14b.
 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 C. Chavel, Sefer HaMitzvot l’haRamban im hasagot haRamban, Mossad HaRav Kook, 1981). “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.’” He 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.
 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 in Megilot, Olam Hatankh.
 Josephus, Antiquities 13:257.