this book is literally the word of god sent to humans. you didn't withness the miracles of jesus, abraham or other prophets but you can read the Quran which talks even about human embryology. How the prophet could know that more than 1400 years? Quran talks also about the real story about jesus. So, once you established that this book is from God with objectif proof, you will confirm that several prophets were sent by God including jesus, abraham and Muhammed peace be upon them all.