Islam is a system of faith.
Islam . It is the world 's second-largest religion and the fastest-growing major religion in the world , with over 1.8 billion followers or 24.1 % of the global population , known as Muslims . Muslims believe that Islam is the complete and universal version of a primordial faith that was revealed many times before through prophets including Adam , Abraham , Moses , and Jesus . Religion is any cultural system of designated behaviors and practices , world views , texts , sanctified places , ethics , or organizations , that relate humanity to the supernatural or transcendental . Different religions may or may not contain various elements ranging from the `` divine '' , `` sacred things '' , `` faith '' , a `` supernatural being or supernatural beings '' or `` some sort of ultimacy and transcendence that will provide norms and power for the rest of life '' .