To most people, faith is a positive quality. Perhaps it is, if "faith" is construed as "hope" or "positive thinking." As in, I have faith that I'll be able to make it to the top of this mountain.
You don't know if you'll be able to reach the summit, but you hope that you will. Nothing wrong with this.
Somewhat similarly, faith can be viewed in probabilistic terms. I have faith that my laptop will start up when I raise the lid in the morning, because so far it has every time I've done this.
But in his book, "A Manual for Creating Atheists," Peter Boghossian defines faith in a fashion that is how religions and other supernatural belief systems use the word.
Pretending to know things you don't know
Ooh! Doesn't sound very positive, does it?
Faith is a deception, a disguise, an effort to fool other people (and yourself). For example, someone who has faith that God exists really is saying, "I'm pretending to know that God exists." Thus faith is a lot like a child pretending to be a princess when she really is just a non-royal four year old in her bedroom.
There's nothing wrong with pretending. Children can get so caught up in their role-playing that it seems real to them. However, when adults do this in the name of their religion it isn't so cute or harmless.
I liked how Boghossian has a table where he has expressions using the word "faith" in one column, and the same expressions with a substituted "pretending to know things you don't know" in another column.
This is a good way of pointing out how problematic faith is. Better to be truthful and honest with yourself and other people. Here's some examples:
"My faith is beneficial for me."
"Pretending to know things I don't know is beneficial for me."
"I have faith in God."
"I pretend to know things I don't know about God."
"Life has no meaning without faith."
"Life has no meaning if I stop pretending to know things I don't know."
"My faith is true for me."
"Pretending to know things I don't know is true for me."
"Why should people stop having faith if it helps them get through the day?"
"Why should people stop pretending to know things they don't know if it helps them get through the day?"
"Teach your children to have faith."
"Teach your children to pretend to know things they don't know."
Here's how Boghossian addresses the faith vs. hope/etc. question.
The term "faith," as the faithful use it in religious contexts, needs to be disambiguated from words such as "promise," "confidence,", "trust," and, especially "hope."
"Promise," "confidence," "trust," and "hope" are not knowledge claims. One can hope for something or place one's trust in anyone or anything. This is not the same as claiming to know something. To hope for something admits there's a possibility that what you want may not be realized.
For example, if you hope your stock will rise tomorrow, you are not claiming to know your stock will rise; you want your stock to rise, but you recognize there's a possibility it may not. Desire is not certainty but the wish for an outcome.
Hope is not the same as faith. Hoping is not the same as knowing. If you hope something happened you're not claiming it did happen. When the faithful say, "Jesus walked on water," they are not saying they hope Jesus walked on water, but rather are claiming Jesus actually did walk on water.
...Much of the confusion about faith-based claims comes from mistaking objective claims with subjective claims. Knowledge claims purport to be objective because they assert a truth about the world.
Subjective claims are not knowledge claims and do not assert a truth about the world; rather, they are statements about one's own unique, situated, subjective, personal experiences or preferences.
...Faith claims are knowledge claims. Faith claims are statements of fact about the world.
...The only way to figure out which claims about the world are likely true, and which are likely false, is through reason and evidence. There is no other way.