When he told his wife, Khadijah about this vision she was sure god had chosen him to be a prophet. Prophet Muhammad began preaching the new religion of Islam. Muhammad recited divine messages he received since he could not read or write. After his death, his recitations were written down, forming the holy book of Islam, the Quran. This is now read by the billions, and memorized by the millions of Muslims across the globe.
A second factor that led to the rapid spread of Islam was the success of conquering lands by the Khalifa (successors) of prophet Muhammad, and the Umayyad Dynasty. The first Khalifas which were close companions of the prophet, Abu Bakr followed by Umar, conquered the great empire of Persia and the byzantine provinces of Syria and Palestine. "Umar also captured Egypt before his assassination by a Persian slave in 644 (331). After the first Khalifs, the Umayyad Dynasty rises."The Umayyad dynasty dominated Islam from 661 to 750" (332). Under the Umayyad rule, Islam expanded even greater. "Muslims advanced west beyond Egypt, conquering all of North Africa and Spain (332)". They also conquered Afghanistan and western Pakistan, with little bloodshed. These conquered lands are one way that led to the rapid spread of Islam.
A third factor that led to the rapid spread of Islam is the concept of jihad. Jihad means the holy struggle or holy war, which some might consider to be the 6th pillar of Islam. There are two different Jihads, the greater Jihad which is" the internal struggle of the soul to be worthy of god and to live according to his principles"(Tames345) and the lesser jihad is "the external struggle, namely, the use of force to fight for one's beliefs"(Tames345). Jihad was usually used in military terms in Muhammad's time, but it was used for defensive measures too. People who died in jihad "are martyrs and are rewarded with immediate entry to paradise" (Tames345), which is an aspect which I think, led to many victories for the Muslims because the Muslims would fight hard and fierce until death.