Religion was created out of human beings fear of death and their uncertainty about what will happen after they die. This, in essence, implies that faith in a god or gods means that they person in question is uncertain about both themselves and about their death. Not that this is necessarily a bad thing, however it is important to note.
By definition faith is not based on proof. It is uncertainty by definition. You cant believe something is real when you know its real. If you know its real you know its real and you dont believe. And with the contradictory beliefs at least most people by far have to be wrong. Not everybody can be right and not every religion can be right and not every denomination can be right. And not every combination of beliefs can be right. But people act like they are certain of their beliefs. Its ridiculous. The world would be a better place if people said i dont know.
Faith doesn't imply uncertainty, it explicitly grants confidence or trust in a particular unknown.
The greater level of faith one has, the less uncertainty that exists in their mind. This is where the potential issue with faith can arise.
Removing that level of skepticism or disbelief can become treacherous when the topic of discussion has any effect on personal behavior, society, legislation, or worldviews.