The reverse of this happened to me today. I am Catholic, as is my boss. We were off at a client's, and at the end of the day we all were discussing when the next time we could get together for the next portion of the job. I made a comment that I wouldn't be here next week (as I'm heading home for the holidays, then off to college), and my boss said something to the effect of "Oh yeah, for Hanukah" and we finished our meeting. As we left, the client wished me "a Happy Hanukah."
Now, I am fairly open to many religions and actually would wish my friends back in high school a happy/merry just-about-every-religious-holiday each year. In fact, my best friend and I used to compete on who could name more holidays than the other. I've been wrestling with my own beliefs for a while now, and am starting to get to a point where I could explain what I believe, and also think myself a rather tolerant person.
All I could to was turn around and walk out. I was too stunned to do anything else.