Cal,
Clearly, and I repeat, the Old Testament is largely trumped by the New Testament. Christianity is based on the New Testament. There is nothing in the New Testament that justified the crusades, inquisition, or any other incident you'd care to mention.
If the Christian religion is to be blamed for those things then the professed disbelief/atheism of Hitler, Stalin, Mao, Pol Pot, et al are to blame for tens of millions of deaths. Communism is specifically a self-professed atheistic movement and communism as exercised by the aforementioned murdered tens of millions.
The Inquisition by comparison is child's play (I think you're talking about a couple thousand). The Roman Catholic church is broken and has been for a very long time. It is why WASPs were unhappy about the large Catholic migration to this country in the past and why they worried about a Catholic president (something I'm sure you agree with

.
The abuse of Christianity may be what Hitchens, you and I can agree on. But you and Hitchens conflate atrocities with the teachings of Christ as a natural by product incorrectly. So that you understand better I should explain that you two are correctly meaning to complain about human nature. Universal atheism will not cure that. As a matter of fact the evidence exists that atheism is the root of greater death and destruction than real faith.
Real faith began when the Protestant Reformation demanded that the Bible be written in the vernacular. That is when people began to learn to read and write. That is when people learned that God wanted a personal relationship with individuals and not through intermediaries like priests and kings. Christian faith is at the root of literacy and individual freedom in this culture. Being able to read the Bible you get that you have no need for priests and kings. And whether you like it or not human nature of the uneducated is to have priests and kings even in a highly technologically advanced culture such as as our own.
spike