In Islamic countries.
because it shapes the conduct of a muslim
No, knowing Arabic is not a requirement to be Muslim. Many Muslims around the world do not speak Arabic as their first language. The most important aspect of being Muslim is belief in the oneness of God and following the teachings of Islam.
The most important belief is that the end of suffering is attainable by following the Eightfold Path.
It is important to have a belief because in most cases it gives your life a purpose.
Pilgrimage itself is a very important belief of a Muslim. It is one of our pillars of ISLAM. our intentions means alot. some people perform umrah before hajj. that is not necessary but contributes to good deeds.
The question as written makes no sense. If you mean "What was the most important Muslim scientific achievement?", see the Related Question below.
Shiite
haaj
Prophet Muhammad (PBUH)
The belief that Almighty Allah (God) is the Only Supreme Authority makes a Muslim dauntless, honest, and truthful.
universities
universities