I know people who's lives have been ruined by religion. I know people who have used religion as an excuse to be violent thugs. Every war on the planet has been fought over religious bullshit.
Actually that is not true. The largest wars were distinctly atheist. Stalinist Russia outlawed religion and the Nazis embraced Nietzsche who said "God is dead."
Pol Pot and Khmer Rouge, nothing to do with religion. Mao se tung, nothing to do with religion.
It is correct that the wars involving Islam are about religion. And of course the crusades were about religion to an extent. But the fact that one needs to go back that far disproves the premise.
People who don't understand religion tend to judge it harshly and unfairly. Religion is what has inspired some of man's greatest thinkers and has been a tremendous source of good. Many of our founding fathers used religion to argue against the slave trade. An argument which eventually won.
Unfortunately, there are a lot of people who use religion as cover for antisocial thinking and behavior and that has a profound effect on how others view religion. People who stand on street corners preaching about the end of the world and how everyone needs to repent are not religious, they are mentally ill. People who read the Bible and take everything literally are likewise a few cards short of a full deck.
If anybody, religious or not, wants to better understand the roots of JudeoChristian philosophy the best place to start is by picking up a book on Talmud or any books that explain the basic tenants of Judaism. Anything written by Joseph Tulushkin is good.
While on the subject, I'd like to say that I have never understood people who hold firm religious views while not understanding the roots of their own faith. I think this is a big part of what causes so much confusion. When you have people trying to interpret a text that is both a discussion on philosophy and law, and those people are unfamiliar with the context in which the discussion takes place, they are bound to misunderstand it.
As is true in life, if we are all free to make up our own interpretation for everything, chaos will certainly ensue.
At any rate, don't be so quick to bash all religious people based on the small group of nut jobs that stands out. For every nut job there are thousands who use religion as a source of moral guidance and genuinely seek to do good.