And if so, what?
I’m not really looking for a debate–hence the forum. I’m just wondering if theists will concede that any conceivable phenomena could make them decide there is no god, and, likewise, if atheists will concede the contrary.
Theist here. Off the top of my head, I can’t think of anything that would cause me to stop believing in God. My belief isn’t based on reason, just a gut feeling. I suppose life experience could make that gut feeling change, but I don’t foresee it happening. It seems like it’s pretty crappy stuff that causes people to stop believing in God. I’ve had my share of crappy life experiences and they’ve all strengthened my relationship with God.
I am curious to see what other theists say and I reserve the right to still their answers if they are any good.
Define “God.” 
I’m an atheist because I believe that the existence of God is an extraordinary claim, backed by no real evidence. If an entity of some sort poofed into existence on the National Mall, and proceeded to demonstrate a series of powers that could be verified by impartial, appropriately equipped observers, then I could believe that this entity existed, and possessed these powers.
For example, if something poofed in and proceeded to make a mountain spontaneously appear, then disappear, created a sheep from mud, cured a man’s cancer with a touch, and so forth, I would believe that this entity possessed those specific powers. I would also believe that it possessed powers reasonably related to the ones it demonstrated - for example, if I saw it move a mountain, and the scientific community was able to confirm it wasn’t a sham, then I’d probably believe (without seeing it demonstrated) that this entity could also move asteroids. Further, if this entity insisted upon being addressed as “God”, I’d call it that - why not?
However, other claims would be a harder sell. Omnipotence, for one. I would only believe that “God” possessed those powers which he/she had demonstrated to neutral, well-equipped scientific observers - since it could never demonstrate an infinite array of powers, it could never demonstrate true omnipotence.
Further, I would be somewhat skeptical of “God’s” claims to have created the Earth, and/or humanity. If it actually created another planet, equipped with a functioning biosphere, that would blunt my skepticism, but not eliminate it - just because “God” could have created Earth, it doesn’t follow that he actually did. We have a fairly good idea of how Earth and humanity things could have emerged without intelligent intervention. In order to believe that “God” actually was the creator, he/she/it would have to present very strong evidence that our current theories are not workable, and that he/she was actually involved in creation.
Finally, I wouldn’t buy any claims of benevolence for an instant. Even if I believed in all the powers that God claimed, I would be shouting for him/her/it to be sent to the Hague as loud as I could. Read the Torah - God has a lot of blood on his/her/its hands.
Atheist here. There is no God. There has never been a God. There’s nothing I can imagine that would change my opinion, because there is no God. You may as well ask me what it would take for me to start believing in Leprechauns.
I think atheists conceded this point a long time ago; all it would take is a measurable and repeatable miracle, and there wouldn’t be any more atheists anywhere. If you want to have a balanced comparison (because of the whole ‘proving negatives’ dealie) is ask atheists if they could conceive anything that would convince them that faith in god is worthwhile, absent evidence.
Well, we’d believe in an entity with the capacity to generate that miracle. That doesn’t mean we’d automatically believe this entity also possessed other powers it hadn’t demonstrated them, or that it had created the world. It would have to slowly, carefully, and thoroughly prove every claim it made.
Would seeing a leprechaun change your mind? Thats what it would take for me, God showing up and doing something that would prove he was God.
I could become a believer. But it would have to be based on the kind of scientific evidence that we use to understand the world today. An event experienced only by me would not be enough; regardless of how intense that event might be. It would be clearly understood by all people simultaneously.
It would have to exhibit power and greatness. It would have to explain why, with all that power and greatness, it chose to create imperfect creatures in an imperfect world.
There would be no secrets and no “trying” to understand its objective. It would have to clearly state its purpose in such a way that all of Earth’s believers would immediately cease to acknowledge their current beliefs and come together in service of the Real Object of Worship.
Okay, seeing a leprachaun would change your mind about the existence of leprachauns. But what would you believe about leprechauns? Would the existence of a small, green man with an Irish accent support a claim that this man also possessed a pot of gold, located at the end of the nearest rainbow?
Of options, I’d generally guess that I was having a halucination. The only practical way for God to prove his existence is for him to simply snap his fingers and toggle the bits in my brain so that I do believe. But even that’s not a proof, since any future tech capable of toggling brain bits could do that same thing. I’d believe none-the-less, of course. It just wouldn’t have been via proof.
If I knew how to falsify it I wouldn’t continue to believe what I currently believe. 
Atheist here. As a child, I believed in God, pretty much because everyone else did, and nobody taught me to think for myself. Then, as an adolescent, I fell in love with this life, on this planet, and found it much more meaningful as something totally real, rather than what people referred to as “spiritual.” I suppose if I ever lose that sense of connection and immediacy, I could believe in God again, but life would become meaningless.
Atheist here, and no, nothing could convince me that there is a god
There…Is…No…God…
Period, stop, End of Line
If I was confronted with an entity capable of producing “Miracles”, I’d see it as nothing more than an an entity capable of manifesting those powers and nothing more, for lack of a better term, an “alien” if you will
Well, as a Catholic, a ground-breaking archaeological dig that discovers a written record of all four+ early Christian communities purposefully making shit up about Jesus (as the atheist says ‘it’s called the Gospels’), would change my belief system for sure.
I wanted to protest this comment slightly. It’s often crappy stuff that makes us begin to question. It’s not necessarily crappy stuff that makes us decide. Decide is almost the wrong word…you just don’t have any faith in you because (and bear with me here) there isn’t anything to have faith in. In other words, there is no faith in us.
To the OP: What would it take for me to believe in a God? I don’t even think a miracle happening right in front of me would make me believe. I would think there was some other scientific explanation, like MacTech. I would be willing to believe the existence of higher life forms such as aliens first of all; they seem to me to be more likely than God, and that’s not saying much.
Even an entity coming to me and saying he was God - I would think it was a hoax, my own deluded imagination, or possibly the alien.
So I guess nothing, really.
When science can provide the answers for unanswerable questions then I guess I won’t “need” to believe.
I don’t think it’s very easy to answer this question, since you can argue away almost anything on either side. Personally, I believe in God because I’ve had experiences that I believe were evidences of him working in my life. Also because the view of the universe I have makes the most sense to me. I can’t really think of anything that will prove the negative to me, but it’s not a scientific, falsifiable belief in the first place, it’s a philosophicalmetaphysical one that just doesn’t get into empirical data.
So–when I die, if it turns out I’m just dead and there’s no afterlife, then I’ll change my mind.
Which one? I can’t think of anything that would change my mind about YHWH, unless It was able to alter my thought process and implant that belief.
Some of the less spectacular deities, the ones that don’t have such fantastical claims made about them would require less effort. If The Dagda appeared with his never emptying cauldron and threw the kind of party he’s known for, then I could probably believe that he was something other than a normal human… or that someone slipped me something really wild, man.
This atheist didn’t stop believing because of “crappy stuff”. Like your belief, my lack thereof is also based on a gut feeling.
So no, there’s nothing that could change me into a believer. If we discover some dude hanging out on a mountain top who can shoot lightning from his fingers, then I’ll believe the evidence that there’s a guy who can shoot lightning from his fingers. Why can he do it? I have no idea, but then again, I don’t know why gravity works either: it does, it’s scientifically proven, and that’s that.
Yes, that is why I used the word “seems”. It appears to me that a major reason that people stop believing (note that I didn’t use the word “decide”) is because of either one horrible event or a series of horrible events. I imagine that it is the series of events combined with our reactions to them that form our gut feelings.