As for the lessons in the allegory, sure those are nice things to teach, but its debatable whether those things can be concluded from the stories. And it's not like ancient Israel is the only place in ancient history that has taught these things.
Sure, but who cares? I'm not arguing for why Christianity is the "right" religion, or that Christianity is the first or only or best teacher of these stories. Just that there's some really powerful truth in its stories. So powerful that it dramatically changed the course of human history. And I know - not always in good ways. Lots of bad, bad things came of Christianity. But like you said, it's not like the crusades are the only time in history that people have conquered other groups because they were different.
I don't know whether I believe that "God did a pretty good job of communicating directly with Abraham", because I don't know that I believe in God as a being that you can communicate with. What I do believe, though, is that there was something special about the story of Christ that made it spread like wildfire. There's a truth - a positive truth - in the words. To me, that truth is God. And God is that truth. Sometimes, you learn something so powerful that you just stop and think, wow. That's what I call God. Whether it's the discovery of a subatomic particle that changes the way we understand the universe, or the moral revelation that we shouldn't leave the world to our children worse than what was left to us, or whatever it is that blows your hair back - that's what I see as God. It's a notion of God that should appeal to theists and atheists alike, at least as a starting point, although they all ascribe different properties from there. An atheist might say, well, truth is truth, there's no magical being who makes it happen. A theist might say, yeah, God is truth, but God is also more than that. I don't claim to know which one is "right"", or if it's more complicated than that, but I'm endlessly curious. I just know we can find some common ground in those core truths, and that's something really positive.
So as far as I'm concerned, fire away if you must. Tell me how you didn't like this story or that story in the Bible, or how Christianity is just an amalgam of other religions. None of that really bothers me, because while I came to a lot of truths I think are Godly by learning about Christianity, I don't see the stories of the Bible as anything more than an interesting way to share the truth. If the stories are all true, or all allegory, or somewhere in between, that's interesting, but it's not the center piece to me, and it doesn't change my faith in the things I do believe in because I've set the bar for my own beliefs so low. I don't presume to know whether everything written in the Bible was copied verbatim over thousands of years, and I don't presume that the world should live by the standards set in that book instead of some other book that they might prefer.
What I do know is that there are some powerful things in Christianity and other religions, and I feel like many atheists dismiss those things without looking for the positives, and cause more strife with theists than they need to. And there's no question that a lot of theists do the same, but worse, pushing their own belief system on other people, using force to enforce that behavior, either the force of law or using force themselves - some bad bad stuff. I don't want to be a part of that. I don't think that's what faith is about.
Let's find some common ground, between theists of different faiths, and even between theists and atheists. We understand a lot of things about the world. We fill in the blanks in different ways, but we should all enjoy the discovery process. Call it faith, call it science, call it curiosity, it doesn't matter to me. We're all on the same tiny rock spinning in the same enormous universe wondering about the same things. We're learning more, faster, than at any time in human history. I feel tremendously fortunate to be a part of that. That's the part I'd like to focus on.