The biblical term "proselyte" is an anglicization of the Koine Greek term ? (proselytos), as used in the Septuagint (Greek Old Testament) for "stranger", i.e. a "newcomer to Israel"; a "sojourner in the land", and in the Greek New Testament for a first-century convert to Judaism, generally from Ancient Greek religion. It is a translation of the Biblical Hebrew phrase ? (ger toshav).
"Proselyte" also has the more general meaning in English of a new convert to any particular religion or doctrine.
The New Testament makes mention of proselytes in synagogues. The name proselyte occurs in the New Testament only in Matthew and Acts. The name by which they are commonly designated is that of "devout men", or men "fearing God", or "worshipping God", "fearers of Heaven" or "God-fearers".
And Pilate, summoning the Jews, says to them: You know that my wife is a worshipper of God, and prefers to adhere to the Jewish religion along with you. ... Annas and Caiaphas say to Pilate: All the multitude of us cry out that he [Jesus] was born of fornication, and are not believed; these [who disagree] are proselytes, and his disciples. And Pilate, calling Annas and Caiaphas, says to them: What are proselytes? They say to him: They are by birth children of the Greeks, and have now become Jews.-- Roberts Translation
There are two kinds of proselytes in Rabbinic Judaism: ger tzedek (righteous proselytes, proselytes of righteousness, religious proselyte, devout proselyte) and ger toshav (resident proselyte, proselytes of the gate, limited proselyte, half-proselyte).
A "righteous proselyte" is a gentile who has converted to Judaism, is bound to all the doctrines and precepts of the Jewish religion, and is considered a full member of the Jewish people. The proselyte is circumcised as an adult (milah l'shem giur), if male, and immerses in a mikvah to formally effect the conversion.
A "gate proselyte" is a resident alien who lives in the Land of Israel and follows some of the Jewish customs. They are not required to be circumcised nor to comply with the whole of the Torah. They are bound only to conform to the Seven Laws of Noah (do not worship idols, do not blaspheme God's name, do not murder, do not commit fornication (immoral sexual acts), do not steal, do not tear the limb from a living animal, and do not fail to establish rule of law) to be assured of a place in the world to come.
The "religious proselytes" spoken of in Early Christian writings were likely righteous proselytes rather than gate proselytes. There is some debate however as to whether proselytes known as God-fearers (Phoboumenoi) and/or Worshippers (Sebomenoi), who were baptized but not circumcised, fall into the righteous or gate category. The New Testament uses the word four times, exclusively referring to converts to Judaism, and never referring to conversion to Christianity.
We know from Pagan, Christian and Jewish sources that during the Hellenistic and early Roman periods some Gentiles were so strongly attracted to Judaism that they became converts and undertook to observe Jewish laws and customs in the same manner as did the Jews themselves. [...] It is also commonly assumed that there were some Gentiles who did not go so far as to become converts but indicated their belief in monotheism and gave up the worship of Pagan gods. How far they went in openly dissociating themselves from Paganism and in associating themselves with Judaism we do not know. These Gentile sympathizers are commonly thought to be referred by the terms sebomenoi or phoboumenoi ton theon and metuentes in Greek and Latin sources, and yir?ê shamayim "fearers of Heaven" (i.e. God-fearers) in some early Rabbinic passages.
Proselytes ad God-fearers.-Many scholars see a parallel between the "God-fearers" in rabbinic literature and the "God-fearers" in the NT. In rabbinic literature the ger toshab was a Gentile who observed the Noachian commandments but was not considered a convert to Judaism because he did not agree to circumcision. [...] some scholars have made the mistake of calling the ger toshab a "proselyte" or "semiproselyte." But the ger toshab was really a resident alien in Israel. Some scholars have claimed that the term "those who fear God" (yir?ei Elohim/Shamayim) was used in rabbinic literature to denote Gentiles who were on the fringe of the synagogue. They were not converts to Judaism, although they were attracted to the Jewish religion and observed part of the law.