It depends really, because from what I can tell most individuals have a faulty idea of what it is, what it means. It seems the general assumption is that faith means to accept or believe things for no reason or evidence, which basically strips it from having any real meaning at all. Faith, as in spiritual faith is supposed to have an actual function or have an actual useful meaning like most other spiritual tools.
I say there's probably three roles (definitions) or usages of faith with "believing in things with no reason or evidence" as the least of them, which is the weakest form of that term. In reality that makes faith a nonword. I mean what is it really to believe something with having no proof or rationale to support it? that's stupid because even to believe in something one must have at least reasoning behind it to accept it and honestly faith is much stronger than belief because it's another word for trust and confidence.
That's really all faith is at its core is to have very strong trust in someone or something. Religions just have their own words to describe something at a spiritual level so both faith and confidence can be used synonymously, however the average atheist would love to rehash the misconception that faith is to just believe in any ol thing with no reason or evidence. Because to them anything pertaining to spirituality is a joke and so that meaningless term just fits the bill for them.
But to have complete trust and confidence (faith) in something is to be based upon very strong reason and evidence no? of course, because one cannot have trust in something without there first being an element that undergirds such a level of confidence. You could say that a married couple who's been faithfully engaged with each other for decades has complete trust in the other person, and their faith in one another is grounded upon years of developing that confidence in one another through experience KNOWING that there is good reason and evidence to believe in their relationship.
If you read the Gospels where faith originated you can see very clearly how faith is depicted. It is based upon ones confidence in God, and ones confidence in God is rooted in experience and good reason, which makes for levels of faith ranging from "small (little) to big (great) faith". "Ye of little faith....ye of great faith".....Because each individual has their own level of trust for God based upon their experience and knowledge. The more experience, evidence and knowledge of God the greater the faith, and the less experience, evidence and knowledge of God the lesser the faith.
This is the second usage of the term faith which brings me to the the third now that we acknowledge faith is based upon strong supporting reason and experience (evidence) to have trust and confidence in something. Without strong reasoning and evidence there can be no trust and confidence in a thing.
The third and perhaps the most beneficial and solid form of faith is what I call an action. This is when a persons faith has become so refined and solidified that a person can put their "faith" in something and cause change, or invoke change. This is also clearly articulated in the Gospels when Jesus talks about faith "moving mountains"....and of course we know Jesus was not talking about rearranging landscapes rather Jesus was saying that faith can be used as a way to bring about results in a persons life (to move obstacles). When a persons confidence and trust (faith) has become an immovable force it can be applied to anything and the potential for anything to happen becomes a reality, they can literally move "mountains", of course that being figurative language to mean "bring about results".
You can see that faith is a universal tool, and people all throughout history have used faith to change the world in many respects, faith can even be used in relation to sports or anything there is a passion to achieve something great. When a person believes (has faith) without wavering (confidence) they can achieve whatever it is they set their faith to. And when you add God to the equation the sky is the limit to what faith can accomplish.
This is somewhat of a rare state to see in this world and you don't see it very often, but there are many examples of people having great faith to change the coarse of the world. Martin Luther King stands out to me at the moment of someone who had great faith to change the world in a time where it seemed impossible to change. His faith overrided reality. But there are many more examples with Jesus being one of them.
People don't really recognize what he did through faith because Christianity has become such a generic force, with little meaning behind it anymore. But in reality Jesus resurfaced the face of religion in a time where religious force ruled the world. Think about one man for a short amount of time coming in and overturning the whole system! Jesus did that with faith being the main source of His achievement. He died for it sure, but not without changing the whole world and how people viewed God. I don't even have to use Jesus as an example, I'm sure you get the point. The point is that faith actually has a legit meaning, even though it's simply trust and confidence given another name. It's anything but "silly".