Unity of Religion
According to Islam, the human intellect, though a great and powerful asset, has its natural limits, and, therefore, neither the normative nor the empirical sciences are capable of leading humanity to a sure knowledge of ultimate truths and the code of life based upon them. The only source of sure knowledge open to humanity is, consequently, Divine Guidance, and that course has been actually open ever since the beginnings of human life on earth. Allah raised His "Prophets" and "Messengers" and revealed His Guidance to them for transmission to humanity. Coming from the same Source, all revealed religions have, therefore, been one, i.e. ISLAM.
Allah's Prophets and Messengers continued to come to every country and community to work in their respective limited fields. Time after time, the revealed Guidance was either lost or corrupted through human interpolation, and new Prophets with fresh Dispensations were sent, and humanity continued to advance from infancy to maturity was reached - when humanity was practically to become one family - instead of sectional Guidance, a perfect, final and abiding Revelation, addressed to entire mankind and for all time, was granted in the seventh century of the Christian era. That Revelation, which recapitulates all former Revelations and thus sets a seal on the Unity of Religion, is ISLAM; The Scripture which enshrines its is the HOLY QURAN; and the Prophet who brought it is the Leader of Humanity, MUHAMMAD (Allah bless him!).
Thus all the Prophets of God, from Adam down to Noah, Abraham, Moses and Jesus (peace be upon them all), are the Prophets of a Muslim, the Holy Prophet Muhammad (peace be upon him!) being the Last and Final one, and all the Divine Scriptures are the Scriptures of a Muslim, though he follows only the Holy Quran because it alone exists in its original purity and it alone contains the religion of Islam which has been followed by all rightly-guided people since the day the first human being came into existence.