well i don't know how really. It depends on what you regard as knowing and how knowledge is accessed. As an agnostic do you feel you are not sure if there is anything over and above the physical.
I am not sure about IsLame, but I am an agnostic too, and I do not believe in the supernatural of any type. But I do not completely disregard the possibility, because if we are not supposed to be able to observe it we would never do. I just can't see evidence and if there's any, I would be glad to change my mind.
"In every time and culture there are pressures to conform to the prevailing prejudices. But there are also, in every place and epoch, those who value the truth; who record the evidence faithfully. Future generations are in their debt." -Carl Sagan