I would probably say something along the lines of:
"[Sister], I understand how this upcoming day is important to you and appreciate that you want me to be a part of it. However, I am an atheist and to sing a song like that would violate my integrity."
Focus on how you're protecting your integrity and that singing that song would be very dishonest. When I finally left the church, the seminary, and the evangelistic series I was preaching all in one conversation what I focused on was that I was no longer a Christian and my integrity demanded that I call it quits. At the end of the discussion I was thanked for my integrity by the seminary professor and ShareHim rep I spoke with.
I wish you the best of luck with this and hope it doesn't cause any deep family issues.
That's really tough. Sorry man. And I was concerned that I'd be asked to pray at Thanksgiving dinner. Hehe, that would have been nothing compared to your sticky situation. Good luck. Let us know what you decide to do.
I just released my second podcast and mentioned your DW Nomad site because that's where I learned about that nut job Michael Travesser and his End of the World Cult. In the episode I talk about the washing in blood lyrics, just like in Shane's video. It all seemed so normal, singing about washing in blood. Now, it's just so sadistic and disturbing. Shane, dare you to put some drops of red food coloring into the baptismal. Praise Jesus, it's a miracle! Sorry, I know that's disrespectful, but come on. Singing about being washed in the blood of a scarified person just asked to be mocked.
At a family dinner after my Grandma's funeral I was afraid I'd be ask to pray since I was the one called on for that for several years worth of family events. My uncle knew I had dropped out of the seminary, but I think that's all he knew. As the time came he looked at me, paused, then asked my dad to pray.
Thanks for the mention on your podcast, I'll have to check it out. If you ever want to have me on I'm always happy to join in on podcasts.
I would absolutely love to have you on some time! I'd be honored. I do want to record an SDA episode or two. Perhaps one going into the history of the church, and another going over more personal experiences with the church. Maybe we can set something up in Q1 of 2012? I'll have to figure out how to use Skype or something.