Analysis of information sources in references of the Wikipedia article "Proselyte" in English language version.
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.
