The Quran tells you to follow the people of the book. The people of the book are the people who follow the previous scriptures. We believe those have been tampered with.
That is a crazy stupid answer do you mean is Allah who wrote the bible when Muhammad was unable to read and write and when the Hadith what ever the Quaran was written by historian it took 500 years the coming of Muhammad after Christianity attacking christians and who remains the truth the bible in short statement what you can preach the Quaran is not the words of God don't compare the word of God with the shit of people