A common one is "But you HAVE to believe in SOMETHING!"
... my usual response is "I do believe in something, reality"
Je m'ennuie parce que je ne connaissais pas de chrétiens fondamentalistes. Mes amis sont indifférents à mon athéisme. Je n'ai pas une histoire humoristique de partager avec vous.
My favorite response:
Me: "I'm an atheist"
Close friend of mine: "What's that?"
Me: "I don't believe in God."
Friend: "Bullshit, you're a christian."
Me: "Yes, (Name deleted.) I'm an Atheist."
Name Deleted: "You're the last person I'd expect to be one."
Name deleted: "You just seem to be a good person."
Gotta love when the town you live in is 90% Catholic.
Me and my mom were talking about how souls and heaven and stuff
Me: So you think once we die, everything in our brain just magically gets teleported to some place in the sky, where we "live" forever?
Mom: No, not our brains, our spirits. You know, us.
Me: But "we" are our brains. Every memory and aspect of our personality is in our brain.
Mom: You're thinking way to hard about this.
I facepalmed in my head
To give a little backstory on me, I've had a lot of awful experiences in my life. I used to be a pretty devout Catholic (taught Sunday school and went to church with my grandmother). I tried to turn to the actual bible for comfort and guidance while suicidal and found none inside, which caused me to doubt Catholicism. That's where this all started.
Lest I give the impression that this wasn't a rational decision, one day I was discussing religion with my fiance and realized that I was basically saying, "Yeah, you Abrahamic religions are so fake, but these ancient Celtic gods who have just as much evidence to support their existence as you do TOTALLY EXIST." Once I realized my hypocrisy, I became an atheist, and it was like a breath of completely rational fresh air.
A few months later, I decided I should tell my "salad bar Catholic" mother that her daughter is a heathen. Here's the conversation.
Me: Mom, I have to talk to you about something important.
Mom: Okay, what's wrong?
Me: Well, nothing's wrong exactly. I just thought I should let you know that I'm an atheist.
Mom: *makes a strangled noise like I'd told her some friends were coming around for dinner and I'd prepared kitten a l'orange.*
There was a very, very long pause.
Mom: You're... you're an ATHEIST? How can you possibly be an ATHEIST?
Figuring it was the best place to start, I thought I should explain the whole process. I tried to enumerate the reasons that had caused me to doubt the existence of a creator as described in the bible in the first place: Emotionally, physically, and sexually abusive boyfriend, broken-up family, divorced parents, one of whom implicitly blames me for said divorce, etc.
Mom: Well, did you ever think god wanted it that way?
We didn't continue the conversation for very long after that, because I saw it was pointless to try and talk about the science I had learned since becoming an atheist, or the evidence that supports atheism (meaning, all of the evidence).
The part that makes me laugh is her hypocrisy. That's probably the single most amoral thing she could have said, and yet she thinks of herself as (and would be lauded as) a "good christian."