Al-Qadar is important to Muslims because: .
it is stated in the qur'an .
it was taught by the prophet muhamed (peace and blessings be upon him) .
Submitting to the will o…f Allah is at the heart of being a Muslim .
It helps Muslims make sense of the world and how it works- Knowing Allah has ilm (knowledge) over everything must mean that everything happen for a reason or a particular cause. Hope that answers the question. ( Full Answer )