It appears that the nature of your error in the math is that you artificially constrain it to the unsupportable notion that if there is a God, He must be able to fit Himself completely in what He created.
On Romans 9, in general I don't subscribe to Calvinist intepretation. If I thought God chose some for damnation, I wouldn't be worshipping Him, as He would be undeserving of my love. I'm pretty sure that the Calvinist strain is a minority angle in Christianity (although may be over-represented in conservative sects, and hence appear central to Christianity, if that's all you know).
I gather that the historic context of this book of the Bible is that most of the Jews were unbelievers (in the Messiah) at the time, and yet God had promised Israel the kingdom of heaven. Paul was speaking to the Jews primarily, basically saying salvation is not a birthright, it comes through faith in Jesus. (9:6 - "For not all who are descended from Israel are Israel.") To them, the Gentiles around you have faith, so they are saved. And if you're angry about that, well, really, who are you question your Creator anyways. God makes the rules, and those are the rules.
But it does not say that it was God who fitted certain vessels for destruction. My Bible cross references 9:22 with Proverbs 16:4: "The Lord works out everything for his own ends -- even the wicked for a day of disaster." God took a haughty, stubborn unbeliever, Pharoah, and used him to show His power, that He is worthy of our respect, and His mercy to the Israelite slaves, despite being imperfect sinners, and therefore that He is worthy of our love. Because we're all sinners, and therefore vessels deserving of destruction. He does things to show the magnitude of His power, and the magnitude of His mercy.
It also does not say that I was fitted for glory. I believe my name was written in the Book of Life before the beginning of (this universe's) time, not because God chose me to be saved, but because He could foresee that I would accept His offer and be saved, and therefore prepared a place for me in Heaven. The off-putting view that God made some of us winners and some losers in the game of eternity is inconsistent with what seems to be our purpose to God. He's looking for us to love Him. Would He pick as winners in eternal life some who do not love Him? Have people in Heaven who are like, meh, about God? Of course not. So only those who love Him will get to Heaven. But then if He hand-picked those who were going to Heaven, He'd have to make sure all the hand-picked loved Him. It seems like the only ways He could do that are, 1) make us automatons and program those He picked for Heaven to have no choice but to love Him, or 2) foresee who would end up loving Him. But if He opted for 1), that's hardly true love.
As for the rest, it's really verse 51 and beyond that you're citing in Luke 12, not 21, but I know your eyesight isn't perfect! But Jesus' (first) coming meant that now there would be the saved and the lost. In the Gospels it says that people will hate believers because of Him. Even within a family there could be strife between the saved and the lost wrt this touchy subject. As for the "black and white thinking", if you don't follow Jesus, then you follow something else; there is no middle ground. God wants us to live His way, and if we choose to live our own way instead, that's in opposition to what God wants.
And let's not even get into what was said about those like me in both the old and new testaments ...
Those like you?