My friend's getting married on Yom Kippur!

When I was choosing my date for my wedding, the first thing I did was bust out the calendar and the Jewish calendar. Its the holiest day of the year. Its your choice whether you want to go or not but if you dont, I would just send her a nice card, and a nice gift. Let her know how happy you are for her, maybe you two can grab drinks when she is back from her honeymoon, etc...

To be fair, the holidays change every year. Its never on the same date, (shit, Hanukkah fell on thanksgiving last year!), so unless she knew to physically look at the calendar, she wouldnt have known.

Would be appropriate to attend the ceremony and not the reception?

When I was looking at venues, many suggested to book on a Jewish holiday since they were generally easier dates to get. FH is a (non-practicing) Jew, and so has Jewish family/friends, so this wasn't an option for us, but I could see why someone who was maybe only expecting one or two Jewish guests might be tempted to pick those dates.

In any case, I think your best bet is to send your regrets with a gift. It is possible she doesn't understand the significance of the holiday, but writing a letter to explain may just make her feel like an ass. Maybe also schedule a lunch date/dinner date with her for after the wedding so you can talk about how it was and look over pictures together.

I think it is totally understandable that you won't be able to attend, and she should completely understand.

However, it is acceptable to get married on a religious holiday…if you aren't that religion. People get married on Christmas and Easter. You pick a day that works for your VIPS and you just have to stick with it. She must have known that she would lose some important people by picking Yom Kippur. I agree send her a present with a lovely note, and try to plan a lunch date to catch up on the festivities.

I’m sorry, but no one looks at a physical calendar anymore, they use the phone on their phone or PC that doesn’t have all holidays visible. It happened to me...I booked my wedding on Rosh Hashana and my best friend who is Jewish, couldn’t attend. I had no idea this date was a Jewish holiday, as I am not Jewish. Just because someone isn’t Jewish like you, you think they should feel like an ass for booking on. Holiday that they weren’t even aware of and were not raised to observe?! Ridiculous!!! What made it worse was my friend didn’t even reach out to me at ANY point during my wedding day, not even a text or anything because she was supposedly at the temple all day. I just don’t agree.