Like you I dod not grow up with the idea of Replacement theology. Honestly, I was more surprised by this Christian theology and other differences within Christianity itself than I was by any differences between Judaism and Christianity! It’s so concerning to realize that so many Christians believe that our God is one that would EVER break a COVENANT. In a theology class at my college, I was taught that the seventh day, the sabbath, is significant because, in Hebrew, the word for seven is also the word for covenant, and in Hebrew tradition covenant signifies a familial relationship. God’s covenant with the Israelites made them his family, his children. A father doesn’t replace his children, though he may adopt more.