Here's another one that gets tossed around a bunch and some times people do not have a good answer for it or argument against it.
"Well, I have FAITH that god exists and that's all anyone needs. Why cant you have FAITH?"
I added to it a little but it's the same idea. As an atheist you will find yourself being villainized for not having FAITH when all of their other points have failed you will be thrown this curve ball.
Ask yourself, what is faith? Does it make sense in this context?
you can continue to believe something on faith but you either begin to believe something because you were indoctrinated into it from childhood or because you had some sort of transformative experience that led you to the truth of a particular faith- and often both together. it's these things that give you faith though there's no evidence.
so i have never had one of these personal transformative experiences and i wasn't indoctrinated from childhood with belief. i have no faith. i can't wake up one day and decide to have faith. at this point in my life, having never been indoctrinated into the belief, i would have to have some sort of personal experience of the type that god apparently, if you accept the claims of many religious people for a moment, brings to many many people. what would it take for you to have faith in the Flying Spaghetti Monster (PBUH)? could you just wake up one day and make a decision to have faith in his complex carbohydrate goodness? so now you see why i can't just decide to have faith in your god either.
so god, being all powerful and all knowing, in having foreknowledge that i wouldn't be brought up in faith and in denying to me one of these personal experiences we hear the religious going on and on about, apparently wants me to remain an atheist. :)
Faith, is this context, usually involves just suspending ones disbelief and accepting without criticism whatever beliefs the theist is promoting. In addition to Nelson's excellent points about how neither faith nor belief can just be 'switched on', I also like to respond that people in other religions (Islam, Judaism, Hindu, Christianity, whichever the theist is not) also claim that just having faith is all that is needed to see the truth of their beliefs, so why don't they try just having faith in that religion?
that's an excellent point and it's similar to my comparison between my interlocutor's god in that case and the FSM. Hindus for instance would say you just have to have faith that Krishna (Vishnu) exists and that's all anyone needs. why can't you just have FAITH!? it's sophistry no matter who's god you swap into the equation. the reason why they can't just switch on a faith in Krishna is the same reason i can't switch on a faith in Yahweh.
Bah, faith. At best it's unnecessary (if you have a real reason to believe something), and at worst it's detrimental to critical thinking (if you don't have a reason, or the reasons you find don't match with the faith, and you choose to stick with the faith anyway).
Faith is pretty much a conversation stopper if you're trying to have a rational discussion. I can't think of any context in which bringing faith into a conversation could be helpful in any sense...
I generally ask them to define faith, then continue like this:
I didn't know having faith was a decision. You just told me it was only a feeling, an inborn knowledge.
If it's rational decision, I've given you my arguments against religion.
If it is an inborn knowledge, I was born without it. That would mean that it was a mistake on god's part. A flawed god can't exist, so it's either me or him in this universe. Can't be both. Who's standing in front of you?
This argument covers two topics for me. The first is abandonment of logic. The second is the personal god and internal feeling of god (evidence not required).
1. Abandonment of logic.
Faith is the antithesis of logic. Once someone decides logic is unnecessary then the floodgates are open. Any argument is fair game. Like "I have faith that God died of a heart attack yesterday at 6:00 pm EST"
2. Personal god therefore evidence not required.
For a long time I thought this was untouchable. Until I saw Sam Harris do it here. http://www.youtube.com/watch?v=XjhbccXIp4c
He's absolutely right. You can easily make a mockery of the idea of a personal god. On any other subject, if a person said they felt something was true, in response to their lack of evidence, then their idea would be immediately discounted.
i love that response. to those that assert that being an atheist lacks faith i respond that that means that they themselves have thousands of faiths. faith in the Christian god AND faith in the nonexistence of Baal, Thor, Krishna, Zeus, Allah, Marduk, Quetzalcoatl, Odin, etc!
watching them stumble around trying to respond is good fun.