Yeah, you might want to save that for a less meaningful family-type gathering!
I can sympathize, it's not my mom or dad, they were conservative to the bone (the reason I am, I'm sure) but I've got an older brother who absolutely hates President Bush and everything he stands for. I find that if I just ignore his comments he stops, because there is absolutely no reasoning with him.
Sorry about your lib older brother. My older brother used to chastise me for being a Dem years ago. A few years back I had to admit to him that he had been right about Dems. But this was only many years after I'd concluded that being a Dem was a waste of time. I was a conservative Dem, but like Zell Miller, I considered it my party. Better late than never. You've got the situation opposite of me. However I do have three liberal sisters who view abortion as sacred. I'm working on them. If I can turn them around, anything is possible. Hope springs eternal and all that.