Of course they should. But as I've stated before many times on here, this is not possible as long as true followers of Islam are among us. I'm not talking about Westernized, modernized Muslims. I'm talking about the serious ones who make up the vast majority of the Islamic world around the globe. And, it is not because I don't want to peacefully co-exist, it is because their definition of "peaceful co-existence" is you and I being submitted to them under Sharia, whether that be willingly by us, or by threat of the sword. That is their definition of peace, which is really no peace at all.
And the point is this - most liberals who put that sticker on their car refuse to acknowledge the truth of what I just said. In fact, most of them would vehemently argue against that truth with some pie-in-the-sky, "Islam is really a religion of peace," rubbish.