Questions on Sects and Schools of Thoughts

Question 38: Does God reward one who believes in Him without necessarily following any particular religion?  If there is indeed such a reward what then would be the importance of following a particular prophet?  If this is not the case, does it mean that it is mandatory to follow one religion such as a monotheistic creed?

Answer 38: It is not possible for one to believe in God and worship Him as He would like to be worshipped without following a prophet.  Consequently, there is no recompense for anyone who does not follow the religion, which God has chosen for His people, and revealed to them, through a prophet.  Faith in God is acceptable only if its object is God and God alone, and if it is based on authentic teachings of a prophet.  All prophets preached Islam which is monotheism, observing of God’s laws, and assenting to the revelation which God sent through them.