or just tell them you're Catholic. works every time!
I had a friend in college who used to carry an official looking contract that he used to pull out whenever he was accosted by Evangelists bearing pamphlets. The contract granted the signer fame and fortune in exchange for their immoral soul. It was really well worded but had a few funny spots like "I ____________ (the Damned), hereby, ...." etc.
He would pull it out after reading the other guys pamphlet and say something like, "thats very interesting, but I think my guy has a better deal to offer. You might be interested in it." They would read it seriously for a moment and then react in one way or another.
When he was not in the mood for the contract thing, he would just look them in the eye and say in a low quiet voice, "I worship the dark thing that lives in the abyss." That usually worked pretty well, too.
Anyway, I think I agree with everyone here. It sucks that they were handing out religious pamphlets for halloween. Its really the parent's business how their kids get indoctrinated (or not), not anyone else's unless designated by the parents.
However, there is no law against what they did and you can't protect your children from the influence of other adults completely. If I were with my kids when the pamphlets were handed out, I surely would have said something about it to them and refused the pamphlets. But if my kids came home with the pamphlets I am not sure I would do much about it.
One exception, though. If the pamphlets were so fundamentalist as to be really scary, I might think about doing something about it. One time in my neighborhood years ago, some really wacky cult was handing out handmade literature that was close to inarticulate. I wasn't home at the time, so they put it in my mailbox. The one they gave me wasn't even a complete sentence, but implied that if I didn't repent right away that I would die. And the word "die" was capitalized and written like a crazy person. As if Charles Manson was my local evangelist or something.
It freaked me out so much that I took it to the local police station and reported it as a death threat.