Re "When you add in Iamblicus’s idea that humans were so fallen they couldn’t return to the gods by theoria (thus needing theurgic erôs/philia": Presumably that was based on his own experience and observation of his fellow Platonists' struggles. Not so different to Indian ideas about the kali yuga and so us needing some kick-arse tantric techniques to liven us up.
Re " theologians used Platonic themes to advance their cause because Christianity was bereft of any substantive content in itself.": Because Christianity isn't a philosophy its a "Way". They used contemporary Platonic categories in the same way a modern theologian would use scientific terms. Re "Nice that you even know about the Platonic tradition.": Yes, it was coming across excerpts in anthologies of Stephen MacKenna's acclaimed translation of the Enneads that intrigued me. (Ie, it was a *literary* thing.) The later Neos like Proclus and Iamblichus are unreadable except by professors in ivory towers. Have you read "Plotinus or the Simplicity of Vision" by Pierre Hadot? Aimed at the layman and grounded in spiritual experience (not getting tied up in conceptual knots).
