Did you do it according to DoD 5220.22-M (overwrite with ones, then zeros, then random bits)? Sanitizing a disk that has been contaminated with the Koran is not a trivial task, you know.
No, I have a better solution. Since I can download the King James version of the Bible after I delete the koran I figure out exactly what sectors the koran was using and then I overwrite them with the Bible.