I think that if one wants to critique Vigano's theology, they should do it when he is writing to Catholics. He is writing to a man who is not a Christian in any palpable sense of the word, and who is of ill moral repute to boot-- who leads a nation of people who are just like him, in a world that is just like him. When the eastern fathers dealt with the emperors in Constantinople (who notoriously vascillated on fundamental dogmas, like the divinity of Christ), I do not think that they communicated with them the same way they communicated with each other at Nicaea. There is a very different vocabulary and purpose at work. It's dumbed down, imprecise, and more aimed at the exhortation of virtue and perseverance than it is catechetical instruction. Yet, it's probably the preferred way of making contact to, say, mailing him a copy of the Roman Catechism.
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I think Vigano is a work in progress; what he says seems to develop progressively over time. This is not dissimilar to reading the Archbishop's material over time, seeing it become increasingly less optimistic (about Vatican II) and more critical. Trying to arrive at a conclusive analysis while the situation is still playing out is difficult, if not impossible.