It's exactly that. Christianity was historically born out of Judaism but (to simplify) in opposition to it. Any belief of Judaism that is not already included i

It's exactly that. Christianity was historically born out of Judaism but (to simplify) in opposition to it. Any belief of Judaism that is not already included in Christianity is not part of the West's cultural heritage, and often in opposition to its values. Supersessionism was challenged only very recently, and out of purely political, not religious or cultural, reasons. Claiming Judeo-Christian roots is a bit like saying that you're genetically the product of your father AND of your paternal great parents- pretty pointless, especially when you fail to mention the maternal contribution.