I'd say, Hello, I am a long-time bible student and I have studied seriously and discovered that Jesus isn't real.

I usually chase them out of my neighborhood. I don't want those assholes anywhere near my kids.

I invite them in and ask questions until they stop having answers.

I meet them at the door with Roger Penrose's excellent book on M theory and the multiverse titled " The road to Reality" and challenge them to a comparison of their book to mine.....They usually take one look at the math involved in understanding M theory and leave without further comment! If that doesn't work I ask them to explain cancer in the light of an all loving god and introduce them to my wife, a 8 year survivor of Pancreatic cancer who was cured not by prayer but by cutting edge science! I then show them the paper we wrote on her treatment that was published in 2016 and ask them to explain why if god was so protective of his followers, my atheist wife survived while several others we knew who were devout and prayed for survival right to the end simply died! The knockers cannot effectively do their task.....people who don't believe because they have thought it out, cannot be swayed by their superficial intellect so they are wasting their time and ours in the pursuit of making themselves feel holy. I think they are the ones that begin conversion with their visit but I don't seek them out they subject themselves to my assault on their superstition and I try to be fully effective! I wonder how many of them actually think about the disquieting things they found at my door?

I have always really enjoyed sharing my experience strength and hope with the Mormons. I live in Idaho so there are plenty of opportunities to do that. I never let them in I will always meet with them outside my front door.
Since my beliefs are very personal to me it is easy for me to share them with others. I don't try to change Minds. And I never ever ever get into philosophical discussions about their religion and the differences we have. I just share my experience strength and hope. Not having an agenda and having pure motives really help as well. As far as the Jehovah's Witnesses that show up they don't really have a desire to talk to me they just want to share the good news. They're going to heaven and I'm going to hell...

I give them about 10 seconds to make sure it is not the Post....then I just shut the door in their face and give them no reaction in a bad or good way. I have been known to say that I just feel sorry for them and once or twice I have asked them if they believe in the Bible and if they say yes I challenge them in a bible quoting contest from memory and I have yet to lose.
Peace to everyone here.

I tell them I am not interested, thank them for coming by & door.

If I'm in a contrary mood, I answer the door naked. They never return. Problem solved. I have enough interruptions without useless conversations.

I have a note on my door strongly discouraging salesman, and bible thumpers. This is my home, and I find it incredibly rude for either of those pests to come knocking on my door. If they read the sign and proceed to knock, then they get cursed out in full force. I do not feel like I have to feel guilty for my behavior as they are the ones being rude and presumptuous.

Well, if it is a Jehovah's Witness, I politely thank them for their decency to stay out of politics. This is one point in their favour anyway. I tell them that i am not interested right now but accept a booklet and they are on their way. The fundamentalist type of born again christians are another story. I tell them to get the hell off my property and stay out of citizens private lives. I have absolutely no liking for them.

Be polite and tell them that you have no interest in the religion business.

If I had time, I’d invite the person in for in interesting conversation. You would both get insight about the other.

I respect as I can every human being. I may not have time to waste on them but... I grew up and was schooled on a Private Catholic Academy. Also attended a Catholic University... I had heard a lot already of what Door-knockers try to offer.

Many years ago I had some Seventh Day Adventists knock on my door. Right at the time I also had a young Dingo Pup ( Native Australian Dog) that my daughter and I were raising.
Right when they started their religious spiel the pup started yelping, it was outside in the back yard at the time, and out of the blue my Daughter suddenly shouted to me, "Dad, you'd better come quick, the baby is trying to eat the dingo."
Funny thing is that my Daughter was an only child and just 7 years old at that time, BUT the dirty looks I got from the Door Knockers were priceless to say the least.

Call the police!

I reply with “In the beginning . . . Man did not understand, so he invented religion to explain everything.” It shuts them up and they go away speechless.

depends on how playful i'm feeling. anything from inviting them in for a drink, smoke, stick or sniff making sure they know contribution and participation is a must. sometimes i'll hear the pitch, look them dead in the eyes and say prove it. I want see, smell, taste, touch or hear it. if I can't do at least one of those. Bye and have a nice day.

I put up a sign on the door telling people that I do not believe and I am happy and content with the world, filled with love and kindness for friends and tolerant of others. If you knock though, all bets are off and the dogs come out.

My son and daughter-in-law have a sign on their door which reads:

NO SOLICITING AND NO PROSELTIZING

THANK YOU

I let them say their piece. It doesn't ruin my day, and it makes them feel like they at least got their chance to "save me". Now if they start getting pushy, or trying to shove things down my throat, then I'll make sure they understand that I'm not interested.

I tell them my sister is waiting for me upstairs in my den of sin, and then ask them if they want to get high and join me.

Knock back

I was in the yard with my Labradors one Sunday and two ladies who were canvassing the neighborhood stopped and saw them, then started asking about them. I had 3 at the time, all girls, 3 generations. The oldest is black and the other two are chocolate. One of them asked if they are related and when I explained their relationship, she was stumped. She asked how they could be mothers/daughters, if they are different colors? I soooo resisted the impulse to say "it's all genetics, or as you would say, God's will". Or, "you wouldn't believe in that". Or some other smart-ass response. I probably went through a dozen of them in my head before I just said "it's genetics, like eye colors in humans". She was pretty stunned by the answer, I'm glad I didn't give her a harsh answer.

To test the waters with a believer - if you want a laugh try - A wise friend of mine would shake his head and with a straight face say, "Oh no, I'm a vegetarian."
If you are trying to be logical with them it won't work. They have wiped that slate clean long ago.

In general believers believe, I believe they need confrontation- they need belief for many reasons - early childhood indoctrination, inability to accept their real worth in the universe, it molds neatly with the other belief nationalism, death scares them, they want to exist by a rule book which makes "THEM" more important in the universe and offers them a reward for using their particular religious playbook (bible, koran - any collection of ancient superstitions/ magic) and they get the DEAL..eternal life in heaven. Also a benefit is social grouping, shared holidays and warm fuzzies which accompany that often reinforced with song, chanting or tongues.

I just say no thank you and shut the door.