My personal view would be
for the really big things (like wars n ting) you can't blame the ideals of religion, but I think it's undeniable that religion enables such actions to be more devastating. For instance, the Crusades were clearly an effort by the Pope to not only make a bit of money but also to unite the warring factions in Europe. The way it was done was sickening, but at its core it was more a power and money thing. The problem I have is this, if it wasn't for the religious reasoning behind it would anywhere near as many people died? Or would the people encountered have been treated anywhere as badly?
Personally my problems with religion lie with its more insidious actions. The indoctrination of children, the criminal negligence of preaching against protection to a country ravaged by AIDS, its ability to influence country politics, or the suppression of women, or how about just the plain violence that's ok because it was done in the name of some beardy? Bashing babies' heads out on rocks, ethnic cleansing, and the treatment of women in captured towns. Sorry, no thanks, I'm not in the business of accepting that something is all right because it's 'religious'.
Every day that I make any effort to find out something new about religion (it still interests me, even though I am more than happy and secure in my 'beliefs') I get more saddened by how easily it pervades everyday life. I really don't bear a grudge against anyone that wants to be religious, but that doesn't mean I'll accept hatred just because it's 'what they believe'.
Apologies for rambling shouty thing.