Very cool. Just curious, did you quote this from somewhere or come up with it on the spot?
Yeah, I kind of like that. 
I disagree with that accessment. While the reply of Revtim was intended to offend, so was his associate’s initial remark. Even without going into all the negative connotations of labelling evolution as a “myth,” his associate still implied that Revtim was stupid because he believed in a myth.
Why else calling Jesus of Nazareth a “myth” rude?
Nah, just invented it.
First of all, I strongly disagree with the concept that the rudeness of a remark is in any way related to whether you know that the person to whom you are speaking disagrees with the comment. If you meet a bunch of complete strangers at a bar and start off your conversation with “Boy, those Republicans sure are idiots,” are you not being rude? If anything, IMO you are being ruder (that word just doesn’t look right) when you assume that your audience agrees with you.
Second (and pardon if I am rude :D) this “emotional investment” or “strong belief” test is balderdash. Rude is rude. The person’s emotional investment merely predicts how offended the person is going to be by the rude statement, not whether the statement is rude in the first place.
Sua
I’m starting to disagree with my original position. I can definitely see the merits of the arguments made by Urban Ranger and Sua.
Ironically, ultrafilter, I was going to back away a bit from my post. I remembered an old Seinfeld episode, where, at a dinner party with his family, Jerry makes a disparaging comment about kids who owned ponies. It turned out that his great aunt had a pony in the Old Country.
Jerry’s comment was still rude, but it would have been ruder had he known about Great Aunt’s pony and still made the comment.
What I’m thinking is that rudeness is (close to) an absolute, but how rude a comment is depends on the circumstances. “Boy, those Republicans are idiots” is less rude when said at a Young Democrats convention then when it is said at a Young Republicans convention, though it’s still rude in either context.
Sua
That the Evolution vs. Creationism is a controversial subject at all causees me to lament the general ignorance of the world.
I think it is rude to parade one’s ignorance or intelligence as though either was something for which one should show off. Had the coworker said, “I’m not aware of the evidence that humans are animals,” that would not have been rude. Saying, “I don’t believe in the evolution myth” is rude because it is an indirect retort to a comment that human beings are animals. Such a comment belittles those who actually have the evidence and study the subject. It is rude, perhaps unintentionally so, but still is rude.
Likewise, parading one’s intelligence can also be rude. Saying, “I don’t believe in the Genesis creation myth” would have been a rude retort, even though it may be a more scientifically supportable belief.