compromise means YOU lose
A while ago, I had the dubious pleasure of watching a youth pastor grow long, floppy ears and start braying. That is to say, I sat in the audience as he ranted and railed about the above-pictured bumper sticker, fuming on and on about the horrible, evil, pluralizing attitude of our secular humanist culture (go figure on that one).
As you might suspect if you speak English, the reality was that he had absolutely mis-read the message of the sticker. Perhaps "mis-read" is a misleading term. I grew up like him and understand him, so I'm pretty sure that he didn't see that sticker at all, but rather that some sort of weird brain cloud got in the way and he ended up seeing something entirely different.
For those who did not, as I did, grow up in Protestant Evangelicalism, I took the liberty of hacking together from a couple of different sources the image that that youth pastor quite possibly saw. Here it is:
While it is of course insanity to see that which is not there, I think perhaps this may help you to understand his emotional response. He viewed the sticker not as call for the religions of the world to co-exist, but rather a call for them all to become exactly like only one of them, the religion of pluralism.
There isn't a religion in the world that wants to become like any other one, and the people who are in a religion get a lot of their identity from that religion's distinct qualities. As a result, any perceived threat to a religion's tenets - be it imaginary or no - is a threat to personal identity, and must therefore be met with extreme force. It makes total, uh, sense.