Okay, your missing an important part here.
Like I said, Christianity and the Mithras cultus existed at the
same time. However, Christianity back then is quite different from what is now because emperor Constantine (lived in Constantinople, now Istanbul (NOT INDIA! That's justwhere the original religion came from)) had the Mithras traditions merged into Christianity to appease his following.
Jesus was born in March, yet here we are, celebrating his birth in December. That's not because we don't know when the guy was born, that's because for political reasons they merged the celebrations. What I was trying to say is that the Bible has changed for political reasons for thousands of year, blurring out the original message. I do think we can learn from it, but you'll have to read through the static of thousands of year of politics. Taking this book literally therefore, seems rather stupid.
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BONUS- The thing we call "the" Bible now is just the King James Bible. This is a Bible composed relatively recently. After he fell out with the Pope he decided to start his own Church. To do that he picked four manuscripts out of hundreds (!) and declared those the true Bible. These manuscripts conveniently suited his views on marriage and other political problems he had. Later on, the rest of the Christians followed his lead and rather than having hundreds of different versions, they adopted these four. Even these four manuscripts differ from each other, but they're even more different from all the Bibles that were thrown away. There were hundreds of versions thanks to an effect like the telephone-game. After retelling the story over and over, elements changed and different versions came to be. Now rather than comparing them to find the original version (or what remains of that) we just picked four. You can ask yourself whether we even have the 'true' version of the Bible now.
As for the Old Testament, that one has been through the ages too. There's been a lot of politics thrown into those too. I like the fact that Muslims/Jews/Christians all share the same base but this base too exists in a wide array of versions since there have been so many edits since it was written.