text: What's more important - what a book says or what the followers do?
  
  Christianity has massacred far more people than Islam. Violence has been a key factor in its success for converting people. Islam was a little more gentle - and that is why it has ruled over other religions like Christianity, Judaism, Hinduism, Zoroastrianism, etc.  In Catholic colonies, it was either conversion or death. A major reason why not a single Muslim or Jew was left in Catholic Spain, Portugal or Italy(or any non Catholics in all of of South America) in the 16th century. Whereas I can't think of a single country where Muslims wiped out the entire local religion.