Misunderstanding "separation," redux

Following on the heels of Rep. Katherine Harris (see here), Julaine Appling, of the Wisconsin Family Research Institute, is reported here to have said, in the context of a same-sex-marriage debate, the "separation of church and state" is a "fictitious wall" and a "fabrication."  Certainly, few concepts are at the same time so important, so misused, and so misunderstood as separation. 

Consider this, from Pope Benedict (in The Salt of the Earth).  After observing that, in fact, it was Christianity that brought the separation of Church and state into the world, he continues:

“Until then the political constitution and religion were always united.  It was the norm in all cultures for the state to have sacrality in itself and be the supreme protector of sacrality. . . .  Christianity did not accept this but deprived the state of its sacral nature.  . . . In this sense, this separation is ultimately a primordial Christian legacy and also a decisive factor for freedom.  Thus, the state is not itself a sacred power but simply an order that finds its limits in a faith that worships, not the state, but a God who stands over against it and judges it.”

Or this, from Deus Caritas Est:

Fundamental to Christianity is the distinction between what belongs to Caesar and what belongs to God (cf. Mt 22:21), in other words, the distinction between Church and State, or, as the Second Vatican Council puts it, the autonomy of the temporal sphere. . . .  The State may not impose religion, yet it must guarantee religious freedom and harmony between the followers of different religions. For her part, the Church, as the social expression of Christian faith, has a proper independence and is structured on the basis of her faith as a community which the State must recognize. The two spheres are distinct, yet always interrelated.