I’ve personally never been approached with the claim that “even atheists have faith in something” - or whatever vague criticism is sometimes leveled at non-believers. Before I declare the common definitions that I’ll be working from, let me say that 1) non-believers are probably wrong to claim that faith and/or belief are stupid, illogical or otherwise untenable as epistemological frameworks; 2) some faith-like or belief-like approaches to living have to be used by everyone, so it’s stupid for a non-believer to claim otherwise.
“Belief is a state of the mind, treated in various academic disciplines, especially philosophy and psychology, as well as traditional culture, in which a subject roughly regards a thing to be true.“
In both cases, the definition “regarding a thing to be true, possibly not based on proof“ seems to match how a non-believer (as I am) applies the terms.
“Faith is confidence or trust in a person, thing, deity, view, or in the doctrines or teachings of a religion. It can also be defined as belief that is not based on proof, as well as confidence based on some degree of warrant. The word faith is often used as a synonym for hope, trust, or belief.”
Let me make my case: every time I need to drive somewhere, I have a reasonable expectation that my car will start, and that I’ll be able to drive wherever I need to go. This is based on 1) a general trust that auto manufacturers want cars to be reliable, thus encouraging repeat sales; 2) experience - it’s been several hundred times in a row since my belief in a functional car has failed me; 3) I generally try not to worry that I won’t be able to do what I plan to do. Otherwise, I’d be an emotional wreck. So - I use what might be termed “faith” as an attitude towards my car.
What would undermine my faith in my car? Well, I bought it used, and for the first several months I owned it, it was a piece of shit. The idiot lights came on, the power steering failed, and eventually the entire electric system shut down. It took several months for the dealer to correct this, during which time I had - with good justification - no faith in this car. It took many months and hundreds of starts to get over the feeling that this piece of shit needed to be junked.
What am I saying?
I started out with faith that this car would work, it let me down and I lost faith, I got it fixed and my faith in it was slowly restored. It was a process, a human, physical process that took about a year.
Now, believers might say “that’s preposterous - faith in God is not like faith in a mere automobile - it's much more transcendent, sublime, meaningful - and the payoff is better!”. To this I say “no, it’s not”. Faith in some unseen entity deserves the same respect as a car does. It has to work. It has to have the properties and behaviors that I expect of it, and when it doesn’t, I need to adjust my expectations of it. And I have done so. God never appears in the universe. Theologians can’t give a clear, unambiguous reason why God would, could or should exist. The world looks exactly like it would if no intervening force were at work, and in the absence of good evidence or good reason to believe otherwise, it makes perfectly good sense to treat God like an automobile that has never and will never work.
It needs to be junked.