Al-Islam is a religion consisted of Aqidah (belief), syariah (law), and akhlak (ethic/moral). Aqidah is a part of Islam which related to belief, which in the heart. Syariah is which related to law, which in word/statement and act/behavior. Akhlaq is which related to relation between human dan other side, which in the heart, word, and act/behavior.
Those parts can not be separated on their application, but interconected to be comprehensive totality. No one can implement rule of syariah correctly and get functions properly, when he quit/omit Aqidah and akhlaq. On the contrary, the truth of Aqidah must be proved by implementation and upholding the rule of Syaria and having holy moral (akhlaqul karimah) as the holy prophet teach.
Aqidah is made up of Tauhid, Nubuwwah, and Baats.