Dictionary definitions for
"faith:"
1. Confident belief in the truth, value, or trustworthiness of a person, idea, or thing.
2. Belief that does not rest on logical proof or material evidence.
3. Loyalty to a person or thing; allegiance: keeping faith with one's supporters.
4. The body of dogma of a religion: the Muslim faith.
5. A set of principles or beliefs.
In examining the question "Is faith beneficial?" I think we'd need to agree on which definition (above) we are using for faith. Or perhaps there's yet another definition?
Let's look for a moment at definition #3. I can see a benefit there. This is almost part of the social contract. When I drive through an intersection with a green light, I have faith the cars that have the red lights will stop (though my faith in even this is sometimes tenuous). When I get married to my wife, I have faith she will love me into the future. Without these kinds of faith, we couldn't drive a car, get married, etc.
If we're talking about definition #2 above, (and it seems we are), I see some benefit there. Most religions have some message similar to: "Be kind to others."
Fine. But why? Why should I be kind to others, really? Sometimes I just get punished for it. Sometimes it seems like a waste. Still, I take it on faith that it is a good thing to do. Our society benefits from people striving toward this ideal. Some of this striving is based on faith. Because speaking in strictly logical terms, there is no real reason to be kind to others. There is no material evidence that shows there is any reason for us to be kind to others. Yet, if everyone does this on faith, the world becomes a better place to live in. Even if the particular religion I happen to believe in turns out to be false.
To put it another way: Lets say I have faith in a simple Christianity. (We could also use the Eightfold path of Buddhism or 10 commandments, etc. for this example). I devote my life to charity, to helping the poor.
(Lets assume I don't get into the darker side of religion like persecution of non-Christians, etc.) So I live out my life like that, and die. Then it turns out that Christianity was all wrong...it wasn't true, whatever. Because of my faith, I still ended up helping others a lot. The faith, even though ultimately possibly misguided, still led me to live a valuable life where I helped others. This is an area in which I see faith to be beneficial, even if it turns out to be a bit misguided. Contrast this to someone who has no faith in anything. They spend their entire life contemplating the nature of the universe, critique every belief system, and end up doing nothing for nobody, because of their lack of faith in anything (hey, thats me if I'm not careful--I better get off my rear).
Extension question: Take someone who has no faith in anything, so they go around critiquing and analyzing everything their entire life. They learn an extreme amount. Yet they end up not really contributing much to society. Take another person who pretty much "takes things on faith," and "freed" in a way by this faith, spends their entire life helping others. Yet the religion they had faith in ended up to be ultimately false. In this case, was that faith still beneficial? Opinion?
And maybe yet another sneaky benefit of faith: It keeps a few whackos from becoming sociopathic murderers, etc., due to fear of punishment by some god. This is debatable, though: perhaps it creates as many psychos as it deters.