That's a tough one to disagree with. So much of modern Western culture has been influenced by Christianity whether it's real or not. I do however disagree with your assertion that without it we would have "all been wild blood thirsty killers by now." without it.
I guess you could argue that Jesus didn't actually do all of those things in the bible and therefore the most important people would be the authors of it who started up this influential religion and not the bible's subject.
Tough case to make though since he was a real person. If someone wrote a fantasy book about Thomas Edison which started up a religion praising him I guess I'd call Thomas Edison the most influential person and not the author of the book. On the other hand if he hadn't existed then obviously the author would be the most influential.
disclaimer: The above post was made with the assumption that the Bible and Christianity are untrue. I apologize if that's hurtful to anyone in the thread but that's my initial position as an atheist and its the angle I'm going to look at this question from.
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