After the periods of the Prophet (S) and the rightly-guided Caliphs, gradually with the passage of time, darkness began to spread in the whole Ummah, and the people of Arabia moved from monotheistic beliefs of Islam to polytheistic acts of the Jahiliyyah period so much so that they again resorted to seeking help of others (than Allah), and flocked around the graves and soothsayers for guidance. Besides there ware so many evils in them that it seemed as if the Jahiliyya days had come again. Imam Muhammad Bin Abdul Wahhab simply called people to Islam - to the Oneness of Allah and a total transformation of life in accordance with the Qur'an and sunnah. In this call, it was quite natural that he had to insist on the pristine purity of Islam at the expense of polytheistic beliefs and deeds, heresies as well as innovations. Many great personalities of Islam in different parts of the world have got inspiration from the life and mission of Imam Muhammad Bin Abdul Wahhab and spread his reformative message in their lands. Indeed it was a great movement which influenced almost all parts of the Islamic world. This book has a lecture on the life and mission of the Imam, which was delivered by H.E. Sheikh Abdul Aziz bin Abdullah bin Baz in 1385 A.H.