Wasn't the Law and the teachings revealed to the Prophet Muhammad, peace be upon him, named only Islam?

The name "Islam" was not restricted to the religion revealed to Muhammad, peace be upon him; rather, it is the name for the religion revealed to all prophets. Allah honored this Ummah (nation) by having the companions and followers of Muhammad, peace be upon him, called "Muslims." Allah mentioned in the Quran that many prophets and their followers were Muslims, which indicates that the Almighty's saying: "And whoever seeks a religion other than Islam, it will never be accepted from him, and in the Hereafter, he will be among the losers," and His saying: "Indeed, the religion in the sight of Allah is Islam," is a general ruling for all, both earlier and later generations. The meaning that their religion is one—Islam—is that they all agreed upon worshipping Allah alone, in accordance with what He commanded and legislated.