Shavuos/Shavuot is one of the three festivals of ingathering, some of our most ancient holidays. On these holidays – Succos/Sukkot, Pesakh and Shavuos/Shavuot, Israelites brought offerings to the Temple to support the priests. Those who had no animals, fruit or grain to bring could buy sacrificial animals at the Temple. (In the Christian Bible, the story of Jesus overturning the tables of the moneychangers refers to those who facilitated the purchase of animals to bring to the Temple.)
Shavuot is at the time of the barley harvest, which is why the Book of Ruth is read on this holiday – the story of Ruth has a pivotal scene at the barley harvest. The Book of Ruth (it’s short and easy to read) explains how the ancients regarded becoming a member of a people – you live among those people and declare yourself to be one of them. No beit din (rabbinic court), no mikveh (ritual bath), no intensive study. Just choosing to live among the people and declare yourself to be one.
This exemplifies our Secular Humanistic understanding of how you become Jewish. You join a Jewish community and identify yourself as Jewish. That’s all it takes. You don’t have to undertake rigorous study (although you can), you don’t have to undergo a humiliating interrogation as to your knowledge and commitment, you don’t have to immerse yourself in a ritual bath. You just say you’re Jewish and be a part of the Jewish community. And you are welcome among us.