Let me guess, the followup is to look at the books in the Old Testament where the requirements to execute homosexuals, adulterers, children who disobey their parents etc are listed, and ask how the Bible can be said to be good?
But sticking with the Qu'ran for now. From what I gather (not being a scholar of Islam by any means) my understanding is that Mohammed had two major phases in his life that corresponded with Mecca and Medina. I forget which way round things went but after one visit he preached a message of peace and after the other he preached a message of war. There appears to be a lot of division within Islam over which overrules the other.
Put in simple terms the early Jewish people had very simple rules and very simple justice - "if someone breaks the rules, kill them". The Jews have advanced beyond that now. Christians have left the bloodier aspects of the Old Testament behind in light of Christ's commands to love. Some would argue that Islam, being a much younger religion, hasn't had chance to evolve from the simplistic "kill them" solution to breaking the rules. Others would focus on the message of peace, and still others would compare the predicted Mahdi who will usher in an Islamic Caliphate to the beast of the Revelation.
