How to tell my friends that I won’t work on Yontif.

So ironically all these friends are Jewish, in fact the thing they’re trying to get me to do is a BBYO board call on zoom. All the other people on my board are very reform and not religious at all, I’m a little more religious and one line I draw is that I won’t do a job on a Saturday (not shomer shabbos) and I 100% keep the high holidays, the second the sun goes down I’m incommunicado. They want me to do a zoom call on Erev Yom Kippur and don’t understand why I won’t do it, how do I tell them I just won’t come if it’s on Yom Kippur?