This will take deep insight into the first and most important pillar of Islam, the two Shahada's.
What are they?
"I have been ordered to fight the people until they testify that there is no god but God and that Muhammad is the Messenger of God, keep up prayer, and pay the zakah (obligatory alms). If they do this they have guarded their blood and property except by what Islam deems lawful. Their judgment lies with God." Bukhari no.25
Its Importance
The second part of the Shahada is the affirmation that Muhammad, son of Abdullah, is the servant, messenger, prophet, and warner from God. He delivered the message, and fulfilled his duty to God and to the world. He advised the people, and God guided the people through him, leaving us on a clear path. He is our leader and our father in faith who came to revive the religion of Father Abraham, monotheism, to a people who corrupted his faith, and instilled a new Covenant, the final Covenant, that unlike the covenants before it, is for all of the world. He guided the world into a new era, by God's inspiration and revelation, into a set of laws that is made for all places and all times, until the Day of Judgement. He came to affirm what came before him in the Torah and the Gospel and to fulfill the promise God made in those scriptures. The only one with authority to intercede for his nation on the Day of Ressurection.