It seems they've been around once or twice a month. Sometimes, they'd come back the next day if you don't answer the door the first time.

How do you go about stopping them from knocking your door or ringing your bell?

You can't just tell them since they are different people and would be impossible to tell them all.

Post a passive aggressive note at the door?

put a cross on your door.... upsidedown... possibly on fire. should do the trick.

I generally scare each group away in person so they don't send anymore, except the Buddhist group I like them they have brought food and don't piss me off.

Tell them to fuck off?

Spray them. Then hit them with a cross and spray again holy water.

Open your door while actively masturbating.

It works like a charm. Not just on religious people, either.

This plus when you orgasm and shoot, quickly yell out " THE POWER OF CHRIST COMPELS YOU!"

I don't know who's knocking on your door but generally fundamental christians tend to be afraid of Catholics. 

I generally just don't answer. Obama sent a lot of people to me near election day, I just hid in my room lol.

He said they tend to be different groups or people, so you would just continue to have to do it to each new person.

But tough luck.  Just have to move I would say.  Where i am now, I never have anyone ever come by to do anything but kids selling school stuff.  The last place I lived I would get people as often as you said.

Obviously I'm ignoring political campaign time.  During that you always get some guy who is running or someone from his family stop by to say hi and drop off a flier, or if not home leave it in the door handle or somethign.