Enjoyably written. However "limpid" means clear and unambiguous, not "limp." So in this case, if the Arian Visigoths actually had possessed limpid Christology, the Iberian peninsula would have been a fierce opponent to Islam, and not softened up for easy conquest.
I point this out because it sticks in my mind after I completely misunderstood the word under somewhat important conditions. On the other hand, it's rarely used, so the error is understandable.
No. He’s saying it was no longer limpid
I think you are both incorrect. Limpid has a wide meaning, and clear, watery, transparent fit his description of a place ripe for conquest.