Why is fasting considered an act of piety?

yes

Explanation:

fasting was something that jesus himself did for 30 days or more

fasting is giving your body for somthing else

hi friend   look late me tall   you with my experience first politic because this subject   it is more politic than be religious   and also give you my experience in islam

first   the islam it is not religion order to kill for we be clear .

so bin laden he not was man of religion   for he use they taught sound islamic theology.

osama bin laden he was influenced by mullah mohammad omar, a very radical manosama bin laden's little understanding of religion has made osama bin laden's speech radical and deviated from the teachings of islam

so the answer > they used radical persuasive rhetoric