There's a guy who shines shoes in my building who greets everyone saying "Praise Him!!" or "Peace, blessings, and grace to you."
My first reaction even though I'm Christian, was damn, I don't want a bible thumper in my face guilting me into saying good morning. But then after awhile I started to notice how good natured he was and he wasn't attacking people, it was just a simple greeting. I've even had a couple of conversations with him and he's not crazy.
OK, then you have the crazy person on the street doing this which is a slightly different circumstance. Some of these people are severely mentally ill. I guess I'm kinda foolish in circumstances like this because I like talking to crazy people unless they seem violent, the likelihood of which increases depending on how close you are to your local VA hospital.
I find the more urban and used to city life you are, the less this offends you. Especially in DC where some of everybody gets up on their soapbox in front of the White House or Capital and starts "preaching." I'm especially fond of the
Black Israelites, they draw quite a crowd!