In considering your question, my thoughts immediately turned to Abraham, whom Jews consider to be the patriarch of our people (incidentally, Christians and Muslims also consider Abraham to be the forefather of their faiths as well).
One of the biblical stories that most illuminates Abraham’s character is found in Genesis chapter 18. Three strangers appear near Abraham’s tent. Abraham hastens to greet them, invite them inside, bathe and clothe them, prepare a meal for them, and share a conversation with them. The lesson is that Jews, the Children of Abraham, are expected to engage in the mitzvah (sacred obligation) of hakhnasat or’him (welcoming guests). What’s more, Jews are expected to welcome guests – even if those guests are complete strangers – in the same manner Abraham does.
If that weren’t enough, our ancient sages believed that Abraham, the first Jew, regularly engaged with non-Jews. He invited them into his home and shared meals with them. He showed them the beauty, warmth, kindness, and joy of his newfound religion. As a result, many of those people followed Abraham and became Jews themselves.
From the very beginning, it has been a central Jewish value to welcome guests, even proverbial strangers who are not part of our people. Doing so offers an opportunity to publicize how the beauty of Judaism. This is good for all Jews. It is a great Kiddush Hashem, a public sanctification of God’s name, ensuring that our God, and therefore our religion, retains a good reputation. It can provide an invitation (where it is welcome) to convert to Judaism, and Jews by Choice bring so much energy and vibrancy to the Jewish community. It helps educate the non-Jewish world about Jews and Judaism, which diminishes the ignorance that fuels anti-Semitism. More importantly, welcoming guests expresses that we view each person who enters our homes as an image of God.
It is, of course, true that there have been Jewish voices that argue we should remain insular and separate, that welcoming in guests and sharing in our traditions should apply only to fellow Jews. In various times and places in Jewish history, this was a life-saving posture: In medieval Europe, for example, when virulent and violent anti-Semitism was the norm, it was simply unsafe to invite a Christian to one’s Sabbath table. In other contexts, we feared that socializing with non-Jews at all, much less inviting them to participate in Jewish rituals, was the first step toward assimilation and abandoning one’s Judaism.
But in our context, when interaction and good relations among various religious and ethnicities is the norm, these arguments no longer hold water. Sharing our traditions with non-Jews poses no threat to Jewish body or soul. Quite the contrary. Jews today should feel empowered to follow the precedent of our father Abraham. I hope your friend continues to invite you for Shabbat, that you continue to attend, and that you now have tools for refuting those Jews who are sadly still stuck in an outdated, exclusionist mindset.