How do we know then that the revelations from Muhammad that he claimed were from Allah were indeed Divine Inspiration ?
The Noble Quran (Allah Almighty's Noble Book) is a book that proved itself to be the Truth. It's Prophecies were all fulfilled. It's Divine Message and strong Literature proved itself to be the Truth among all of the pagan Arabs who all latter embraced Islam. Muhammad was predicted to come in the Bible. The Message of the Oneness of Allah Almighty and the sacrifices that Muhammad peace be upon him has put to embrace it and spread it only prove that he was indeed the True Messenger of Allah Almighty. Islam's "Oneness of GOD" Message came and conflicted a great deal with the Pagan Arabs customs, culture and business, because they worshiped more than 360 idol gods, and those idol gods were the main factor for generating money for them. Muhammad and his followers were forced into so many challenges/battles and survived all of them and by the Will of Allah Almighty were able to ultimately defeat all pagans and make the entire Middle East a Muslim region. How could Muhammad and his Message survive all of this if GOD Almighty wasn't backing him up all the way? How else would a True Messenger from Allah Almighty prove himself to be truthful?