Calvinism is Biblical
You believe in a Covenantalist Bible interpretation method. As opposed to a more literal Dispensationalist Bible interpretation method.
For a quick recap:
Running through Romans 9 with the two different interpretation methods will result in opposite conclusions.
3 For I could wish that myself were accursed from Christ for my brethren, my kinsmen according to the flesh
Covenantalist interpretation: The part about flesh and kinsmen is ignored or spiritualized, as Covenantalism does not make physical and spiritual distinct
Dispensationalist interpretation: The part about flesh and kinsmen is emphasized, setting this chapter as a chapter about the physical part of things.
4 Who are Israelites; to whom pertaineth the adoption, and the glory, and the covenants, and the giving of the law, and the service of God, and the promises;
Covenantalist interpretation: Since Israel and Church are the same, the chapter is about all saved.
Dispensationalist interpretation: Since Israel and Church are separate, the chapter is about only Israel, and no one else.