Really? Then how come in Christianity the central tenet is personal salvation by a personal relationship with God?
Actually the notion of Christianity as a personal relationship with God is relatively recent. Historically Christianity has been viewed by Christians and by non-Christians as a collective entity. Remember, not every collective institution is a statist one. Families are collective institutions, for example. I think the author's point is that Democrats dismiss all these collective social institutions (except for the government) and they are foolish to do so, given the way humans are hard-wired.
Yup. That notion is unique to American Protestantism and, to a degree, post-Vatican 2 American Catholicism.
It's what prompts Alan Bloom to declare that American Christians are really closet Gnostics. I think he's right, to an extent.