What is so important about faith?

Greetings. As I said, I would have a question. It is there in the title, but I will repeat it:
What is so important about faith?
I will now add some explanation. Most major world religions have a component involving faith on the part of the adherent. Faith is important, it moves mountains, it is like a mustard… but why? I have been thinking about this, and I cannot come to a good answer, so I ask you, my loyal readers, to answer me. Why faith? Why is it that faith has no evidence, and that is lauded, even to the point where asking questions (perhaps even the one I am asking) is considered taboo, and showing a lack of faith. I am just curious about this, and am curious to see your replies…

dy/dx e^x = e^x

S