Is Religion a Force for Good or Evil?

In eastern europe in the early middle ages, about 1/3 of the population was killed in religious wars.  Then there was the 100 years wars.  And let us not forget that when the Israelites  moved into Cannan they killed all the non virgins, and most of the animals.

So it depends on your definitions of good and evil, but when it comes to war, I can not think of a greater motivator than belief in a pure just and righteous god.  

Should someone point out that the Russians and Rhineese killed a lot more people than any religions, but that is only because they had better technology and more people to kill.  Given  the technology available in the early middle ages, killing of 1/3 of the population  really shows the power of god.

 Of course, it's a force for good.  But there are evil people and evil people always try to use something good and bend it toward an evil purpose.

So it can get hijacked just like everything else.

The problem is when you no longer believe in good and evil, or truth vs. lies, etc.  Then you have no orientation and can't discern an evil person from a good one or their truths vs. lies from a stick in your @$$.