Absolutely - I'll leave my last word to quote Sam Fleming from the guest book who has indeed been at this a long time. She has written some very good articles on the subject, including why chalking stones is bad:
http://www.ravenfamily.org/sam/pag/rrtart1.htm

Guys, been dealing with people like this for years, as some of you know.

Threats of violence will not help. They'll make Mike feel persecuted, and that's going to make him more entrenched and more convinced that the world needs saving and he's doing the right thing.

He needs someone to explain to him what they problem is. Not using threats of violence, but the way you might explain about the birds and the bees to a youngster.

Seriously. I understand why you're angry, believe me I do. Taking that anger out on Mike, however, isn't going to achieve anything and might make things worse.

Sam Fleming