Sometimes they go a bit further and ignite debate, such as the one in front of the Church of the Nazarene in this San Francisco suburb. It's promoting a Sunday sermon titled, "Why I am not a Muslim."

"I thought, 'That is an offensive sign, per se,'" said Jay Keller, who lives around the corner. "I work with a lot of Muslims and don't know why someone would put up a sign like that. They can't possibly be oblivious to the fact that it might be offensive to some people." ...