Boyd K. Packer has said, "Faith, to be faith, must center around something that is not known. Faith, to be faith, must walk to the edge of the light and then a few steps into the darkness.
If everything has to be known, if everything has to be explained, if everything has to be certified, (that is knowledge) then there is no need for faith. Indeed, there is no room for it." 3 Nephi 26:11 says in part, "I will try the faith of my people."