I'm Jewish- I think Harry's ultimatum was very realistic. Yes, he's not particularly observant. However, Judaism has been rendered into a race/ethnicity over time, not least of which by anti-Semites who want to destroy the Jewish people. There's an element of cultural pride/familial obligation/defiance to refuse to abandon the Jewish people and participate in the erosion of the group by marrying and raising children outside of the faith and to leave a even smaller, even more vulnerable Jewish population as your legacy by taking your children outside the group. He's also profoundly culturally Jewish- Yiddish in conversations, Jewish food, holidays. It makes sense that he'd really care about having a household that matches his identity. I'm Jewish and living with and contemplating marriage to a Catholic man. I'm not really observant either but being Jewish is quite important to me. I won't ask him to convert because his Catholicism is about as important to him as my Judaism is to me. We're not devout or even particularly observant but it's a crucial part of our identity and we celebrate the holidays and milestones of our faith. Our parents are even more religious. They support our relationship and unlike Harry's mother, they haven't demanded a promise to marry within the faith. However, I think his dad and my mom would REALLY have problems with their child converting. We've discussed that we'll just figure out compromising on having a place for both faiths in our future family- but I anticipate that it'll be complicated. Now, I don't think Charlotte cared as much about Episcopalianism as Harry and I care about Judaism or my boyfriend cares about Catholicism. In the conversion storyline, Charlotte mourns giving up Christmas but we never really see her celebrate holidays or look forward to raising her children specifically within a faith. In the series, it looks like she took to being Jewish more than she did Episcopalianism. LOL, I get why- we've got awesome food, cute Yiddish words to sprinkle in conversations, a looooong, fascinating history, very social synagogues that take marriage and having kids very seriously, and holidays that encourage liberal consumption of wine.