Islam has two meanings; general and linguistic. Islam in general refers to the way of life which God sent His Prophets to teach mankind: The worship of God alone (Monotheism) and the avoidance of Paganism while submitting to God's will in gratitude for being given life and innumerable blessings. This explains why, in the Qur'an, all Prophets call themselves Muslims (submitters to the will of God). I don't think anybody would rationally claim that God sent different religions as this would cause confusion and would ultimately lead to social conflict. God clearly states in the Qur'an that he has been enjoining Islam upon mankind since Adam and Eve. This way of life -Islam- consists of worshiping God alone and submitting to His will.
