We don't have many of these people here but I did once receive a flyer from a local 7th day adventists. I took their flyer and a copy of FFRF newsletter and left it at the doorstep of their meeting hall. I thanked them for their information and just thought I'd give them additional information in return.

Step 3 works for me.

I'm polite until it doesn't work, then I become rude,and probably start swearing.

"Your god is a genocidal maniac. Get used to it."

Where I live the only unwanted door knockers are JW's and Baptists. If we exchange words the Baptists finally tell me to "look at the trees." I guess that is their proof of their god.

The only solicitors I get are from people trying to scam you over the phone, which I don't answer, unless I'm expecting a call. On the few occasions I do get one on the other end, I simply laugh at them and hang up.
When I lived in Colorado, I used to get the JWs and LDSers, for whom I simply didn't answer the door.
There are companies out there that sell life-size, realistic-looking fake alligators to put in your front yard. One of those would scare off even the most determined JW!

Slip in a fresh clip.

I like the method a family friend had, it took a little upfront work but seem to have permanent results.
First, he got a clerical collar (Halloween costume). When they came to the door, he invited them in.
When they started talking about the bible, his gig was "please wait, I need my collar before talking about the bible." Then he would grab the collar, put it on, and "where were we?". That typically ended the conversation quickly. He was quite versed in the bible if they persisted.
After 3 visits from different groups, he never got bothered again. Put him on the "don't go to this house" list.

It was back in the 80's. They might have become more persistent now.

Well, I think this might work. Probably workds better for men than women ...

The last proselytizers showed up a few months ago when I was WFH. I just happened to be available to answer my door, and I saw the buybulls in their hands, I didn't even let them say anything, I said "get the fu$k off my porch and never come back. And put me on your list of houses to avoid." Then I shut the door and went back to my computer. I have not been bothered since then, but then again I'm working in an office again so I'm not home most of the day.

A friend of mine had a method that he said worked every time. Living in west Texas, he often got those same door-knocks, though it was usually the holy-roller's. When they asked if they could discuss their buddy Mr. Jesus, he'd say sure, so long as I can discuss Buddhism with you. He had a 100% success rate.