Hi Leolaia,
I didn't mean to question your understanding of this issue, I just tried to clear a possible misunderstanding by your readers, in view of the topic title and op. You have made excellent points as ever.
One thing I find striking is the difference between Paul and Justin in their reappropriation and distribution of OT material to the "Father" and the "Son". It seems to me that Justin's criterium is mostly contextual (no matter how fanciful his exegesis can look to us): wherever Yhwh acts on the earthly scene or is perceived by senses (seen, or heard) in the OT narratives, the corresponding character is identified with the second "God/Lord," i.e. the Son. Otoh, Paul's criterium seems to be purely verbal: wherever the word kurios is used, regardless of the narrative (or discursive) context, the material can be ascribed to the Son, whereas the word theos is restricted to the Father, in both OT quotations and autonomous Pauline writing. Of course the general thrust of the argument is different, too: Justin, addressing a "Jew," strives to distinguish the Son-God from the Father-God while Paul mostly tries to establish a practicalequivalence between them (implying that relationship with the "Lord" Jesus counts as relationship with "God"). The distinction is only implied in the overall movement of the Pauline Christ-myth: God sends his Son and, at the end of his mission, the Son submits to the Father so that "God is all in all" (1 Corinthians 15).
However, what I think needs to be stressed is that Christian theology always rests on a redistribution (the terms of which differ from one author to another) of the OT Yhwh/God material between two (and eventually three) figures, neither of which can be simply identified with "the OT God".