Right, but the claims here are different from the claims you initially made, and are much more minimal (though no less controversial). And the formula that you cite regarding Paul's apparent denial of the identity of Christ and God the Father hinges on interpretation of what exactly the Greek term
kyrios is supposed to signify in relation to its Hebrew root, the human
adon or the divine
adonai. The fact that Paul immediately uses the
shema formula in 1 Cor 8:6 while mentioning the lack of reality for Jews of multiple gods in 8:5 with relation to both God the Father and Jesus Christ as Lord also provide structural context for identification, because it would be exceedingly odd for Paul to claim simultaneously that 1.) there are no more than one divine entity and 2.) that both God the Father and Christ are divine personages through which redemption and bringing into the law occur. See:
This interpretation neglects the fact that ‘one Lord’ is not something brought to Deut 6:4, as an additional ‘one’ alongside the ‘one’ God. Rather, κύριος is the divine name in apposition to ὁ θεός in Deut 6:4 itself. The “one nation” of 2 Sam 7:23 presented as a parallel to the εἷς κύριος of 1 Cor 8:6 is, in the end, a red herring; κύριος is the name of the “one God,” a name that picks out the same being as θεός does in Deut 6:4, and that name is now applied to Ἰησοῦς Χριστός. Jesus is thereby identified with God as the co-bearer of the divine name. ("Paul and the Trinity: Persons, Relations, and the Pauline Letters", Hill, Wesley, 2015)
Also see
The numeral 'one' that is attached to both 'God' and 'Lord' does not set up two competing entities, but it unites in singleness the being and act of God as Father ("One God and Trinitarian Language in the Letters of Paul", Mauser, Ulrich, Horizons in Biblical Theology, 1998, Vol.20 (1), p.99-108)
But also see:
All of this seems deliberate on Paul's part. That is, he is reasserting for the Corinthians that their theology has it right: there is indeed only one God, over against all other "gods many and lords many." But at the same time, he insists that the identity of the one God also includes the one Lord; and ultimately he does so because (1) this is the now shared Christian perspective about the one God and (2) it is the inclusion of Christ as Lord in God's identity that will give Paul the leverage to forbid attendance at pagan festive meals. ("Christology in 1 Corinthians", Fee, Gordon F., "Pauline Christology", p.91)
Evcn Matthew V. Novenson, who is on the non-identity camp, makes a stronger claim for the divine statue of Jesus than what you seem to be imputing. See:
Paul’s Christ is not identical with God, but he stands in a closer relation to God than any other divine being does. In the letters of Paul, angels and demons are called angels and demons, not ‘sons of God’, as they often are in the Hebrew Bible (e.g., Ps 29:1; 89:7; Job 38:7). For Paul, only Christ is the son of God, with the rule-proving exception of people who get joined to Christ and thereby become sons of God themselves (Rom 8:14, 19; 9:26; Gal 3:26; 4:6–7). Christ is, moreover, ‘the image of God’ (2 Cor 4:4), the visible representation of the invisible God (analogous to the measure of the heavenly body of God [shiʿur qomah] in late antique Jewish mysticism). God’s glory (that is, his kavod or bodily presence) has always been hidden in his sanctuary in Jerusalem (Rom 9:4), but in the new creation, all human beings (not only priests but also laypeople, not only Jews but also gentiles) can attain ‘knowledge of the glory of God in the face of Christ’ (2 Cor 4:6). The divine pneuma (usually translated ‘spirit’) that people receive in the new creation is, at the same time, the pneuma of God and the pneuma of Christ (Rom 8:9). Paul’s Christ is the son of God, the image of God, the face of God. These descriptions are tantalizingly brief, but in one passage Paul supplies a narrative within which their sense becomes a bit clearer (Phil 2:5–11):
"Christ Jesus, who, although he was in the form of God, did not consider it as spoils to be equal with God, but he emptied himself, taking the form of a slave, being in the likeness of humans; and being found as a human in regard to figure, he humbled himself, becoming obedient to the point of death, the death of a cross. Therefore indeed God highly exalted him and gave him the name higher than every name, so that at the name of Jesus every knee should bow, of beings in heaven and on earth and in the underworld, and every tongue confess that Jesus Christ is lord to the glory of God the father."
In this fascinating passage, Christ is neither God nor human, exactly. He exists in the heavenly form of God, but his likeness and figure are human. He undergoes the quintessentially human experience of death (and thus is a mortal, strictly speaking), but he receives obeisance from human and superhuman beings like a high god would.37 Like Metatron in the Jewish mystical text 3 Enoch, Christ in Philippians 2 is both a deified human being and the archangelic form of God. ("Did Paul abandon either Judaism or Monotheism", Matthew V. Novenson, New Cambridge Companion to St. Paul, 2020, p.252)
Which certainly isn't the trinitarian formula as conceived by the creedal churches, but is way more "high" than simply considering Christ as God-chosen. Already the hypostatic union is being pressaged in these passages, and Paul uses language that is reminiscent of the incarnation.
But even Novenson admits that the identification of Jesus with God is earlier than the 4th century A.D., as you posit:
Admittedly, Titus 2:13 arguably does call Jesus a god: ‘the appearing of the glory of our great god and savior Jesus Christ.’ (ibid., p.251)
2 Titus is written way before the 4th century A.D, unless consensus has shifted massively. I think there's an argument to be made that Paul didn't consider Jesus identical with God (and I think he would have been wrong in intending the text in this manner upon revelation from God, but that's a theological question, not exegetical), but in Pauline scholarship your claims are definitely suspect regarding the nature of the shema. As for the concept of the trinity, at the very least its found in the Didache in the 1st century AD, so Augustine was simply reacting to a much older tradition that would become orthodoxy.
I am not as well-versed in Johannine scholarship, I will admit, so I can't really talk about there. Though I'd be skeptical of consensus regarding the shema there too.