I’ve read that before common era, it was a common practice for Gentiles to associate with Jewish congregations without intent to convert. Why was this a common practice, and why has this practice become almost extinct?
Regarding the second part, I’m also interested in why very few, if any, religious congregations are welcoming of those who would associate without conversion.
I believe that in biblical (Old Testament times until the period of Hillel), there was not any concept of “conversion”. Israelites where physical descendants of Abraham, Isaac and Jacob and Gentile “believers” (sometimes called “God fearers”) were “part of the community” but still Gentiles - not “Israelites” or in today’s usage, Jews. The concept of “conversion to Judaism” evolved over time.
Its a little blury because there are some pretty “famous” non-Jews who make up part of Jewish patriarchical history - Ruth (a Gentile) marrying into a Jewish family and then marrying Boaz and King David and Jesus appearing in that “line” - same with Rahab (a Gentile) - in the line leading to Christ.
There are many reform Jewish congregations that freely invite Gentile/non-converts to fellowship and be part of the community.
There are probably some books that expound upon this history, I haven’t checked but if you are interested you might look into that further .
There were gentiles who believed in the God of Israel and worshipped him but who didn’t circumcise themselves or bind themselves to Jewish law. I’m guessing they followed the Noahide laws… Anyway, there was an outer court in the Temple where they were allowed to come and worship. They just didn’t join the chosen nation.
Scott Hahn likes to talk about how the Mosaic Covenant was only for the Israelites, but the Davidic was international. I suppose you could call the Noahic covenant international, too.