Islam originated in the 7th century in Saudi Arabia. Hence, Islam is the youngest of the main religions in the world. Prophet Muhammad introduced Islam in 610 AD after experiencing the visit of Angel Gabriel.
According to Islamism, the Qur'an (its Holy Book) is supposed to be of divine origin since it was dictated from Allah to the Angel Gabriel and from the latter to Prophet Muhammad. In other words, Muslim doctrines began long before Muhammad walked on earth since they were transmitted by Angel Gabriel to said prophet.
