They do not teach religion in public school. In the United States, anyways. They certainly are not teaching that Abraham was an actual historical figure, because there is nothing to back that.
Romans persecuted Jews, even obliterated their country and made it disappear from the map. Literally. They persecuted Jews for a couple of thousand years. Where have you been? Jesus was a Jew. Jesus did not preach Christianity. There was no such thing to preach back then.
Cyrus the Great was God? He wasn't even Jewish.
Messiahs, like King Cyrus, are not God or the sons of God, they are liberators of the Jews who would then lead the country into a period of peace and prosperity. That's what a messiah does. That is something Jesus never did. Ever. Not even slightly. Bar Kokhba did lead a revolt against the Romans and set up a region that was independent of them for a few years. He was a messiah, do you worship him as the Son of God?
The Gospels were written a century or more after, whatever they say about prophecy, isn't. Writing a century or for later that something fulfilled prophecy is irrelevant. Last thing Jesus told his followers is that he would be back within their lifetimes, before their generation came to pass. Unless you got some 2,000-year-old Judeans hiding out somewhere, Jesus is going to be a little too too late to his own party.
Almost as many people as there are Christians believe that there is a God with a human body and an elephant's head with blue skin. Nearly as many Christians also believe (at some point in their life, anyways) in Santa Claus, the Easter bunny, and the Tooth Fairy. Call me an apostate, but I don't believe Rudolph the Red-Nosed Reindeer is real.
I'm not having a discussion anymore with somebody in 9th grade, I'll end up saying more about your religion that you will regret, and I'd rather not do that. I already excised a small portion that would have.