Islam was the religion of Adam, Abraham, Moses and Jesus. God addresses this issue in the Quran with regard to Prophet Abraham, saying:
Abraham was neither a Jew nor a Christian, but he was an upright Muslim who did not worship others besides God. (Quran C3:V67)
Since there is only One God, and humankind are one species, the religion which God has ordained for human beings is one. He did not prescribe one religion for the Jews, another for Indians, yet another for Europeans, etc
WHO IS KNOWN AS MUSLIM ?
A Muslim is an adherent of Islam. The Qur'an is the holy book of Islam and Muslims believe that it is the verbatim word of God as revealed to the prophet Muhammad. Muslims also follow the teachings and practices of Muhammad as recorded in traditional accounts called hadith. "Muslim" is an Arabic word meaning "one who submits to God". A female Muslim is sometimes called a Muslimah.