When did that happen? Can you document it in scripture? I don't think we can assume anything.
It is doubtful that most early churches had anything close to a complete NT. And it is likely that most churches did not have an OT due to the expense and the attitude of Jews against Gentiles..
Here is about 1/4 of the negative attitudes against gentiles I found in the Jewish Encyclopedia
Jewish Encyclopia-Gentiles
Gentiles May Not Be Taught the Torah.
Inasmuch as the Jews had their own distinct jurisdiction, it would have been unwise to reveal their laws to the Gentiles, for such knowledge might have operated against the Jews in their opponents' courts. Hence the Talmud prohibited the teaching to a Gentile of the Torah, "the inheritance of the congregation of Jacob" (Deut. xxxiii. 4). R. Johanan says of one so teaching: "Such a person deserves death" (an idiom used to express indignation). "It is like placing an obstacle before the blind" (Sanh. 59a; Ḥag. 13a). …
Resh Lakish (d. 278) said, "A Gentile observing the Sabbath deserves death" (Sanh. 58b). This refers to a Gentile who accepted the seven laws of the Noachidæ, inasmuch as "the Sabbath is a sign between God and Israel alone," ... Rabbina, who lived about 150 years after the Christians had changed the day of rest to Sunday, could not quite understand the principle underlying Resh Lakish's law, and, commenting upon it, added: "not even on Mondays [is the Gentile allowed to rest]"; intimating that the mandate given to the Noachidæ that "day and night shall not cease" ((Heb.)Lo yshabti = "have no rest ") should be taken in a literal sense (Gen. viii. 22)—probably to discourage general idleness
"The Torah outlawed the issue of a Gentile as that of a beast" (Miḳ. viii. 4, referring to Ezek. l.c.)
Johanan bar Nappaḥa … the Torah was given as a heritage to Israel, a non-Israelite deserves death if he studies it (Sanh. 59a).
Gamaliel also expresses himself to the same effect, adding that the Gentiles, by their impure motive, incur the penalty of Gehenna. Eleazar of Modi'im sides with him, saying that "the Gentiles practice benevolence merely to taunt Israel."
Eliezer b. Hyrcanus is …, the mind of every non-Jew is always intent upon idolatry (Giṭ. 45b). The cattle of a heathen is unfit for sacrifices ('Ab. Zarah 23b). Explaining Prov. xiv. 34, he maintains that the non-Jews only practise charity in order to make for themselves a name (B. B. 10b; Pesiḳ. 12b; Gamaliel is credited with the same opinion in B. B. 10b).
Joshua b. Hananiah, … as a rule Gentiles cling to vain things and are rejected (Prov. xxviii. 19; Gen. R. lxxxii.).
GENTILE - JewishEncyclopedia.com