The combination of a "no soliciting" sign in my yard and an anti-proselytizing symbol in the window next to my front door has been very effective at deterring proselytizing Christians. I would say that it has reduced non-religious solicitation by at least 90% and Christian proselytizing by roughly 80%. What else could an atheist do to make it clear that he or she wants to be left alone by those wanting to spread the "good news" about their mind virus? A reader emailed me this picture of a welcome mat he had made, and I am quite jealous.
The only drawback I see is that it can't be seen from the street, which means that the purveyors of delusion will likely leave their "literature" on one's porch. But that also means the neighbors won't see it every time they drive by, and that might not be a bad thing.