Faith is one of the hardest subjects to both grasp and accept. People often think that having faith and knowing something are the same. There is a relationship to them that is valuable to understand.
Merriam-Webster has this (among many) definition for the word "Faith", and it best applies to what I am trying to explain here:
"firm belief in something for which there is no proof"
Merriam-Webster provides the following definition of "Know":
"to be aware of the truth or factuality of: be convinced or certain of"
We can chase definitions all day long, and it wouldn't be without merit, but it would become a rather long path to a short statement. There are distinct differences between these two items.
Faith includes words such as "belief" and "no proof". There is a relationship here of "DESPITE". Meaning even without proof, there is still belief. It is incredibly subjective in nature. It is a personal conviction.
Know on the contrary has "truth or factuality" and "certain". These carry a relationship of "BECAUSE". Meaning the facts convince the person into knowing. It is objective. It can be widely shared concept.
Neither of these take away from the other. Both are important.
I am a Christian. I have a faith in the Christian Doctrine and the words expressed in the Holy Bible. I have faith that Jesus the Christ died on the cross for my sins, taking them from me, and allowing me to be be seen as good and perfect before my God. I do not know that I am right in this, but I move forward none the less. Anything I know is either anecdotal, meaning specific to my observations and experience that is not scientific in nature or process; or it is a knowing based on what I learn from the texts and teaching I believe in. So I can know something within my faith, but I cannot apply it to others outside of my faith.
In other words, I do not hold the world outside of me to things I know inside my faith. If my knowing is based on my faith, and others do not carry that same faith, how could they know it as well.
This is why so often I have to correct Christians when they address the world that does not believe as they do, that they cannot say things like, "It's true because the bible says so!" They forget that their faith exists in a bubble that includes other people who believe the same, but not for the world outside that bubble.
I hope this helps.